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Monday, August 28, 2023

Climate change in the Middle East and North Africa

Köppen climate classification maps for the Middle East at present (top) and predicted for North Africa for 2071–2100 (bottom).

Climate change in the Middle East and North Africa (MENA) refers to changes in the climate of the MENA region and the subsequent response, adaption and mitigation strategies of countries in the region. In 2018, the MENA region emitted 3.2 billion tonnes of carbon dioxide and produced 8.7% of global greenhouse gas emissions (GHG) despite making up only 6% of the global population. These emissions are mostly from the energy sector, an integral component of many Middle Eastern and North African economies due to the extensive oil and natural gas reserves that are found within the region. The region of Middle East is one of the most vulnerable to climate change. The impacts include increase in drought conditions, aridity, heatwaves and sea level rise.

Sharp global temperature and sea level changes, shifting precipitation patterns and increased frequency of extreme weather events are some of the main impacts of climate change as identified by the Intergovernmental Panel on Climate Change (IPCC). The MENA region is especially vulnerable to such impacts due to its arid and semi-arid environment, facing climatic challenges such as low rainfall, high temperatures and dry soil. The climatic conditions that foster such challenges for MENA are projected by the IPCC to worsen throughout the 21st century. If greenhouse gas emissions are not significantly reduced, part of the MENA region risks becoming uninhabitable before the year 2100.

Climate change is expected to put significant strain on already scarce water and agricultural resources within the MENA region, threatening the national security and political stability of all included countries. Over 60 percent of the region’s population lives in high and very high water-stressed areas compared to the global average of 35 percent. This has prompted some MENA countries to engage with the issue of climate change on an international level through environmental accords such as the Paris Agreement. Law and policy are also being established on a national level amongst MENA countries, with a focus on the development of renewable energies.

Greenhouse gas emissions

See also: Greenhouse gas emissions accounting
Green house gases being emitted from a chimney in a natural gas and oil field in Western Iran.

As of January 2021, the UNICEF website groups the following set of 20 countries as belonging to the MENA region: 'Algeria, Bahrain, Djibouti, Egypt, Iran (Islamic Republic of), Iraq, Jordan, Kuwait, Lebanon, Libya, Morocco, Oman, Qatar, Saudi Arabia, State of Palestine, Sudan, Syrian Arab Republic, Tunisia, United Arab Emirates, Yemen.' Others include Israel as well.

Greenhouse gas emissions produced by humans have been identified by the IPCC and the vast majority of climate scientists as the primary driver of climate change. In the past three decades, the MENA region has more than tripled its greenhouse gas emissions and is currently emitting above the global average per person, with most of the top ten countries by carbon dioxide emissions per person being found in the Middle East. These high emissions levels can be primarily attributed to Saudi Arabia and Iran, which are the 9th and 7th largest emitters of CO2 in the world, accounting for 40% of the region's emissions in 2018. MENA countries heavily rely on fossil fuels for the generation of electricity, sourcing 97% of their energy from oil, natural gas, and coal (in Turkey). Fossil fuel extraction, production and exportation is also a significant component of many economies within the MENA region, which possesses 60% of the world oil reserves and 45% of known natural gas reserves. Reducing gas flaring would help.

The failure of the Iranian subsidy reform plan during the 2010s left Iran as the world's largest subsidizer of fossil fuel in 2018. But, unlike other countries which successfully removed subsidies by acting gradually, at the end of the decade, the government attempted to suddenly reduce gasoline subsidies, sparking riots.

Impacts on the natural environment

Temperature and weather changes

Heat extremes

The IPCC project average global temperatures to rise more than 1.5 degrees by the end of the 21st century. MENA has been identified as a hotspot for future temperature changes due to its arid environmental conditions. Whilst projected rates of warming during winter months are low, the region is expected to experience extreme temperature increases during summer. Temperature rises are expected to be further amplified by reductions in rainfall and the associated depletion of soil moisture, limiting evaporative cooling. As a result, heat extremes are expected to increase significantly in both frequency and intensity across the MENA region. According to studies published by the Max Planck Institute for Chemistry, the number of very hot days in the region has doubled between the 1970s and the time when the report was published (2016). The study further projects that heatwaves will occur for 80 days of the year by 2050 and 118 days of the year by 2100. Combined with increased sandstorms associated with longer drought periods, predicted temperature rises would make large parts of the region uninhabitable.

The average maximum temperature during the hottest days of the past 30 years has been 43 degrees Celsius. Dutch atmospheric chemist Johannes Lelieveld has projected that temperature maximum's could reach almost 50 degrees Celsius under current climate scenarios established by the IPCC. Johannes Lelieveld further projects that average summer temperatures are expected to increase by up to 7% across the MENA region, and up to 10% in highly urbanised areas. Extreme heat has been identified as a serious threat to human health, heightening an individual's susceptibility to exhaustion, heart attack and mortality. Climate scientist Ali Ahmadalipour has projected heat-related mortality rates within the MENA region to be up to 20 times higher than current rates by the end of the century.

  • Köppen climate classification of MENA in the present and the future
  • Western Asia in the present

    Western Asia in the present

  • Western Asia in the future

    Western Asia in the future

  • Northern Africa in the present

    Northern Africa in the present

  • Northern Africa in the future

    Northern Africa in the future

Water resources

See also: Water conflict in the Middle East and North Africa
A Sudanese farmer and his land. Drought and low rainfall has severely reduced the farmer's capacity to grow crops.

The Middle East and North Africa currently faces extreme water scarcity, with twelve out of the 17 most water stressed countries in the world deriving from the region. The World Bank defines an area as being water stressed when per person water supplies fall below 1,700 cubic metres per year. The water supply across the MENA region is averaged at 1274 cubic metres per capita, with some countries having access to only 50 cubic metres per person. The agricultural sector within the MENA region is heavily dependent on irrigation systems due to its arid climate, with 85% of fresh water resources being utilised for agricultural purposes. The IPCC indicate that the global distribution of rainfall is currently shifting in response to increasing greenhouse gas emissions, with increases in high latitude and mid-latitude wet region and decreases in equatorial dry regions such as the MENA. These shifting precipitation patterns have already placed significant strain on MENA agriculture, with the frequency and severity of droughts rising significantly in the past decade.

A recent NASA study suggests that the 1998–2012 drought in the Middle East was the worst to occur in the past 900 years. Climate scientist Colin Kelley suggests that climate change was a significant contributor to the increased severity of the most recent drought in the region. He claims that such drought is 3 times more likely to occur due to human influence on climate and the drought have contributed to the beginning of the Syrian civil war. Along with environmental impacts, increasing drought periods affect agricultural incomes, diminishes public health and weakens political stability in the MENA region. Syria experienced its most severe drought on record from 2007 to 2010, where restricted water supply degraded agricultural resources and increased economic pressures. American environmental scientist Peter Gleick also asserts that heightened social vulnerability and conflict over scare water supplies during this period catalysed the onset of the Syrian war.

However, in 2017, a study led by sociologist and political ecologist Jan Selby has discredited these claims, reporting that there is no solid evidence that climate change is associated with the drought, the same about the impact of the drought on the conflict in Syria. In 2019 Konstantin Ash and Nick Obradovich published research indicating that extreme drought was one of the leading factors in the creation of the Syrian war.

Increasing water insecurity as a result of climate change is set to exacerbate existing food insecurities in the countries affected. A study published by the World Food Programme has predicted a decline in crop yields by 30% in 2050 as a result of increasing droughts. North African countries are highly vulnerable to reduced precipitation, as 88% of the region's crops possess no irrigation, relying on consistent rainfall. The consequences of these reduced harvests strongly impact rural regions and communities that rely heavily on agriculture as a source of income.

Sea level rise

The coastline of Alexandria, Egypt's 2nd largest city.

Alexandria is one of the most vulnerable cities to sea level rise.

Across the MENA region, 60 million people inhabited coastal areas in 2010, a population that has been predicted by the World Bank to grow to 100 million by 2030. As a result, the population of the MENA region is expected to be significantly impacted by sea level rise occurring due to climate change. One consequence of rising sea levels is the loss of coastal wetlands, a natural resource responsible for ecosystem services such as storm buffering, water quality maintenance and carbon sequestration. A study conducted by the World Bank predicts that the MENA region would lose over 90% of its coastal and freshwater wetlands if a one-metre sea level rise were to occur.

In North Africa, Egypt is expected to be most affected by changes in sea level. A third of the Nile Delta and large parts of Alexandria, Egypt's second-largest city, lie below the mean global sea level. These areas have been drained for agricultural purposes and undergone urban development, where inundation and flooding is prevented by sea walls and dams. However, failures occurring in these structures, storm surges and extreme weather events could lead to the inundation of these areas in the future if sea levels continue to rise. Agricultural areas in Egypt are particularly at risk, where a one-metre rise in sea level would submerge 12–15% of the nation's total agricultural land. This is estimated to displace 6.7 million people in Egypt and affect millions more who rely on agriculture for income. A more moderate 50 cm increase in sea level has been projected to displace 2 million people and generate US$35 billion of damages.

Mitigation and adaptation

The severe impacts of climate change on the region, made climate change mitigation and adaptation an important issue in it. Regional cooperation is considered as one of the main conditions for effective mitigation and adaptation.

Renewable energy

Mohammed VI of Morocco speaking at the COP22 climate summit held in Marrakech.

The MENA region possesses high potential for developing renewable energy technologies due to the high levels of wind and sunshine that are associated with its climate. The International Renewable Energy Agency (IRENA) has identified over half of all land in GCC states as being suitable for the deployment of solar and wind technologies. IRENA has also identified North African countries as having greater potential for wind and solar energy generation than all other regions of the continent. Sourcing energy from renewable technologies instead of fossil fuels could significantly reduce energy related GHG emissions, which presently account for 85% of total emissions within the MENA region. Renewable energy generation also involves significantly less water usage than processes associated with fossil fuel extraction and its conversion into usable energy, possessing the potential to improve water quality and availability within the region. Renewable energy presently accounts for 1% of the total primary energy supply across the MENA region.

At the 2016 UN Climate Change Conference in Marrakech, Morocco (COP22), Morocco, Tunisia, Yemen, Lebanon and the State of Palestine, along with 43 other countries, committed to deriving all energy from renewable resources by 2050.

Ouarzazate Solar Power Station

Ouarzazate Solar Power Station, Morocco.

The Ouarzazate Solar Power Station is a solar power complex located in the Drâa-Tafilalet region of Morocco, and is currently the largest concentrated solar power plant in the world. The complex consists of four separate power plants that utilise concentrated solar power and photovoltaic solar technology. The project, costing US$2.67 billion, is expected to provide 1.1 million Moroccans with clean energy and reduce the country's carbon emissions by 700,000 tonnes every year. The total energy capacity of the solar plant is expected to reach 2000 Megawatts by the end of 2020.

Policies and legislation

Paris Agreement

Further information: Paris Agreement
Countries which have not ratified the Paris Agreement shown in yellow

Eleven countries from the MENA region attended the 21st Conference of the Parties of the UNFCCC where countries negotiated the Paris Agreement, an agreement with the United Nations concerning greenhouse gas emissions mitigation. As of 2021 Eritrea, Iran, Iraq, Libya, and Yemen are the only countries in the world which have not ratified the agreement. Morocco has set its nationally determined contribution to a 17%-42% reduction in emissions and has set a target of having 52% of renewable energy in its total installed electricity production capacity by 2050. The share of renewable energy reached 28% in 2018 and is currently recognised by the United Nations as being on track to achieving its renewable energy targets. The UAE, despite ratifying the agreement, have set no reduction in emissions in their nationally determined contribution. The United Nations have identified their NDC target as "critically insufficient".

MENA Climate Action Plan

In 2016 the World Bank put forth the MENA Climate Action Plan, a series of financial commitments centred around the redistribution of finance to the MENA region. The World Bank deemed the plan's core focus to be ensuring food and water security, increasing resilience to climate change impacts and improving investment in renewable energy source. One of the Action Plan's major commitments was to allocate 18-30% of MENA finance towards climate related initiatives, which currently stands a $1.5 billion annually. The World Bank have also outlined a significant increase in funding directed towards adaptation initiatives such as water conservation and recycling, introduction of desalination facilities and investment into carbon sequestration technologies.

By country

Algeria

Temperature anomaly in Algeria, 1901 to 2020.
Climate change in Algeria has wide-reaching effects on the country. Algeria was not a significant contributor to climate change, but, like other countries in the MENA region, is expected to be among the most affected by climate change impacts. Because a large part of the country is in already hot and arid geographies, including part of the Sahara, already strong heat and water resource access challenges are expected to get worse. As early as 2014, scientists were attributing extreme heat waves to climate change in Algeria. Algeria was ranked 46th of countries in the 2020 Climate Change Performance Index.

Egypt

Further information: Environmental issues in Egypt and Climate of Egypt

Egypt's Nile Delta is impacted by saltwater intrusion caused by sea level rise, leading to major implications for the country. Agriculture and food security in Egypt will be disrupted by climate change due to increased drought, higher temperatures, extreme weather events, plant diseases and pests, with major infrastructure changes required to adapt. Water security in Egypt will also be disrupted.

Iran

Lake Urmia has shrunk due to reduced inflow in recent decades. This is attributable to climate change, and contributes to water scarcity in Iran.
Climate change in Iran is leading to an increase in average annual temperatures and a decrease in annual precipitation. Iran is the largest greenhouse gas emitter not to have ratified the Paris Agreement. The country is experiencing a greater frequency of flooding and extended periods of drought due to climate change. Climate change also has implications for water scarcity, agriculture and human health in Iran.

Iraq

Climate change in Iraq is resulting in effects that are making Iraq's environmental, security, political, and economic challenges worse. Rising temperatures, intense droughts, declining precipitation, desertification, salinization, and the increasing prevalence of dust storms have undermined Iraq’s agricultural sector. Additionally, Iraq’s water security is based on the declining Tigris–Euphrates river system. National and regional political uncertainty will make mitigating the effects of climate change and addressing transnational water management very difficult. Climatic changes such as increasing temperatures, reduced precipitation, and increasing water scarcity will likely have serious implications for the state of Iraq for years to come. Greenhouse gas emissions per person are above the world average.

Israel

Further information: Climate change in Israel and Environmental issues in Israel

According to the Ministry of Environmental Protection of Israel: "While Israel is a relatively small contributor to climate change due to its size and population, it is sensitive to the potential impacts of the phenomenon, due to its location. Thus, it is making an effort to reduce greenhouse gas emissions while simultaneously doing whatever possible to reduce the expected damage that will result if climate change is not halted."

The impacts of climate change are already felt in Israel. The temperature rose by 1.4 degrees between 1950 and 2017. The number of hot days increased and the number of cold days decreased. Precipitation rates have fallen. The trends are projected to continue. By the year 2050, in the coastal area the number of days with maximal temperature above 30 degrees, per year, is projected to increase by 20 in the scenario with climate change mitigation and by 40 in "business as usual" scenario.

Israel ratified the Paris Agreement in 2016. The country is part of 3 initiatives on mitigation and adaptation and 16 other actions taken by non-governmental organisations.

According to Israel's Intended nationally determined contribution the main mitigation target is to reduce per capita greenhouse gas emissions to 8.8 tCO2e by 2025 and to 7.7 tCO2e by 2030. Total emissions should be 81.65 MtCO2e in 2030. In the business as usual scenario the emissions would be 105.5 MtCO2e by 2030 or 10.0 tCO2e per capita. To reach it, the government of Israel wants to reduce the consumption of electricity by 17% relative to the business as usual scenario, produce 17% of electricity from renewables and shift 20% of transportation from cars to public transport by 2030. In an effort to comply with GHG emission reductions, Israel formed a committee with the goal of evaluating the country's potential to reduce emissions by the year 2030. Their findings have confirmed that Israel's power sector generates approximately half of the country's total GHG emissions. The second-largest offender is the transport sector, which produces approximately 19% of total emissions.

Jordan

Jordan is mostly desert.
Climate change in Jordan has serious impacts on the water resources in Jordan. The country needs to prepare for the impacts of climate change. Water resources in Jordan are scarce. Besides the rapid population growth, the impacts of climate change are likely to further exacerbate the problem. Temperatures will increase and the total annual precipitation is likely to decrease, however with a fair share of uncertainty. Hence, existing and new activities with the objective to minimize the gap between water supply and demand contribute to adapt Jordan to tomorrow's climate. This might be accompanied by activities improving Jordan's capacity to monitor and project meteorological and hydrological data and assess its own vulnerability to climate change.

Kuwait

Further information: Climate change in Kuwait

Morocco

A dried body of water in Agadir. Climate change will increase the frequency of drought in Morocco.

Climate change in Morocco is expected to significantly impact Morocco on multiple dimensions, just like for other countries in the MENA region.

As a coastal country with hot and arid climates, environmental impacts from climate change are likely to be wide and varied. Analysis of these environmental changes on the economy of Morocco are expected to create challenges at all levels of the economy. The main effects will be felt in the agricultural systems and fisheries which employ half of the population, and account for 14% of GDP. In addition, because 60% of the population and most of the industrial activity are on the coast, sea level rise is a major threat to key economic forces. As of the 2019 Climate Change Performance Index, Morocco was ranked second in preparedness behind Sweden.

Sudan

Drought conditions near Khartoum.
In Sudan, climate change has caused an increase in temperatures, a decline in rainfall and driven desertification. Climate change poses significant challenges for rainfed agriculture and therefore the entire economy. Analysis of weather patterns suggest drought conditions and other extreme weather increased in Sudan during the 20th century. The relationship between climate change, water conflict and the war in Sudan has also been a topic of academic debate.

Syria

Main articles: Environmental issues in Syria and Climate change and the Syrian civil war

Turkey

road with large cracks being washed away by a roiling brown river
Flash floods are predicted to become more frequent as here in Sinop.
Climate change in Turkey includes changes in the climate of Turkey, their effects and how the country is adapting to those changes. Turkey's annual and maximum temperatures are rising, and 2020 was the third hottest year on record. Turkey will be greatly affected by climate change, and is already experiencing more extreme weather, with droughts, floods and heatwaves being the main hazards.

United Arab Emirates

In 2010, UAE examined with the support of the Stockholm Environment Institute's US Center the effects of increasing carbon dioxide emissions and its impact on the weather. The report investigates the effects of climate change on the economy, the infrastructure, the health of citizens and the entire ecosystem. It resultants with a dramatical impact of rising sea levels by affecting 6 percent of its coastal urbanization by the end of the century. The scenario of one-meter sea level rise would lead to UAE's loss of 1,155 square kilometers of the country's coast by 2050. Nine meters of sea level rising would flood almost all of Abu Dhabi and Dubai.
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North African climate cycles

From Wikipedia, the free encyclopedia

North African climate cycles have a unique history that can be traced back millions of years. The cyclic climate pattern of the Sahara is characterized by significant shifts in the strength of the North African Monsoon. When the North African Monsoon is at its strongest, annual precipitation and consequently vegetation in the Sahara region increase, resulting in conditions commonly referred to as the "green Sahara". For a relatively weak North African Monsoon, the opposite is true, with decreased annual precipitation and less vegetation resulting in a phase of the Sahara climate cycle known as the "desert Sahara".

Variations in the climate of the Sahara region can, at the simplest level, be attributed to the changes in insolation because of slow shifts in Earth's orbital parameters. The parameters include the precession of the equinoxes, obliquity, and eccentricity as put forth by the Milankovitch theory. The precession of the equinoxes is regarded as the most important orbital parameter in the formation of the "green Sahara" and "desert Sahara" cycle.

A January 2019 MIT paper in Science Advances shows a cycle from wet to dry approximately every 20,000 years.

Orbital Monsoon Hypothesis

Development

The idea that changes in insolation caused by shifts in the Earth's orbital parameters are a controlling factor for the long-term variations in the strength of monsoon patterns across the globe was first suggested by Rudolf Spitaler in the late nineteenth century, The hypothesis was later formally proposed and tested by the meteorologist John Kutzbach in 1981. Kutzbach's ideas about the impacts of insolation on global monsoonal patterns have become widely accepted today as the underlying driver of long term monsoonal cycles. Kutzbach never formally named his hypothesis and as such it is referred to here as the "Orbital Monsoon Hypothesis" as suggested by Ruddiman in 2001.

Insolation

Insolation, which is simply a measure of the amount of solar radiation received on a given surface area in a given time period, is the fundamental factor behind the Orbital Monsoon Hypothesis. Due to variations in heat capacity, continents heat up faster than surrounding oceans during summer months when insolation is at its strongest and cool off faster than the surrounding oceans during winter months when insolation is at its weakest. The wind pattern that results from the continent/ocean insolation temperature gradient is known as a monsoon. Values of summer insolation are more important for a region's climate than winter values. This is because the winter phase of a monsoon is always dry. Thus the flora and fauna of a monsoonal climate are determined by the amount of rain that falls during the summer phase of the monsoon. Over periods of tens to hundreds of thousands of years the amount of insolation changes in a highly complex cycle that is based on orbital parameters. The result of this cycle of insolation is a waxing and waning in the strength of the monsoonal climates across the globe. A wide range of geologic evidence has shown that the North African Monsoon is particularly susceptible to insolation cycles, and long term trends in monsoonal strength can be linked to slow variations in insolation. However, the abrupt shifts back and forth from the "green Sahara" to the "desert Sahara" are not entirely explained by long term changes in the insolation cycle.

Precession

Precession of the equinoxes on Earth can be divided up into two distinct phases. The first phase is created by a wobbling of the Earth's axis of rotation and is known as axial precession. While the second phase is known as apsidal precession or procession of the ellipse and is related to the slow rotation of the Earth's elliptical orbit around the sun. When combined these two phases create a precession of the equinoxes that has a strong 23,000 year cycle and a weak 19,000 year cycle.

Variations in the strength of the North African Monsoon have been found to be strongly related to the stronger 23,000 year processional cycle. The relationship between the precession cycle and the strength of the North African Monsoon exists because procession affects the amount of insolation received in a given hemisphere. The amount of insolation is maximized for the northern hemisphere when the precession cycle is aligned such that the northern hemisphere points toward the sun at perihelion. According to the Orbital Monsoon Hypothesis this maximum in insolation increases the strength of monsoon circulations in the northern hemisphere. On the opposite end of the spectrum, when the Northern Hemisphere is pointed toward the sun during aphelion, there is a minimum in insolation and the North African Monsoon is at its weakest.

Obliquity

Obliquity, otherwise known as (axial) tilt, refers to the angle that Earth's axis of rotation makes with a line that is perpendicular to Earth's orbital plane. The current tilt of Earth's axis is roughly 23.5°. However, over long periods of time the tilt of Earth's axis of rotation changes because of the uneven distribution of mass across the planet and gravitational interactions with the Sun, Moon, and planets. Due to these interactions the tilt of Earth's axis of rotation varies between 22.2° and 24.5° on a 41,000 year cycle.

Modulation of the precession driven insolation cycle is the primary impact of obliquity on the North African Monsoon. Evidence for the impact of obliquity on the intensity of the North African Monsoon has been found in records of dust deposits from ocean cores in the Eastern Mediterranean that occur as a result of Aeolian processes. This evidence requires complex feedback mechanisms to explain since the strongest impact of obliquity on insolation is found in the high latitudes. Two possible mechanisms for the existence of an obliquity tracer found in the Eastern Mediterranean Aeolian dust deposits have been proposed. The first of which suggests that at times of higher obliquity the temperature gradient between the poles and the equator in the southern hemisphere is greater during boreal summer (summer in the northern hemisphere). As a result of this gradient the strength of the North African Monsoon increases. A second theory that may explain the existence of an obliquity signature in the North African climate record suggests that obliquity maybe related to changes in the latitude of the tropics. The latitudinal extent of the tropics is roughly defined by the maximum wandering path of the thermal equator. An area that today is located between the Tropic of Capricorn and the Tropic of Cancer. However, as the obliquity changes, the overall wandering path of the thermal equator shifts between 22.2° and 24.5° north and south. This wandering may affect the positioning of the North African Summer Monsoon Front and thus impact the perceived strength of the North African Monsoon. Further confirmation of the impacts of obliquity on the North African Monsoonal have been provided through a global fully coupled atmosphere–ocean–sea ice climate model, which confirmed that precession and obliquity can combine to increase precipitation in North Africa through insolation feedbacks.

Eccentricity

Orbital eccentricity is a measure of the deviation of the Earth's orbit from a perfect circle. If the Earth's orbit was a perfect circle then the eccentricity would have a value of 0, and eccentricity value of 1 would indicate a parabola. The Earth has two cycles of eccentricity that occur on cycles of 100,000 and 400,000 years. Over the years the Earth's eccentricity has varied between 0.005 and 0.0607, today the eccentricity of Earth's orbit is approximately 0.0167. While the value of eccentricity does impact the distance of the Earth from the Sun, its primary impact on insolation comes from its modulating effect on the procession cycle. For example, when the orbit of the Earth is highly elliptical one hemisphere will have hot summers and cold winters, corresponding to a larger than average yearly insolation gradient. At the same time the other hemisphere will have warm summers and cool winters due to a smaller than average yearly insolation gradient.

Like obliquity, eccentricity is not considered to be a primary driver of the strength of the North African Monsoon. Instead eccentricity modulates the amplitude of the insolation maxima and minima that occur due to the precession cycle. Strong support for the modulation of the precession cycle by eccentricity can be found in Aeolian dust deposits in the Eastern Mediterranean. Upon close examination it can be shown that periods of low and high hematite fluxes correspond to both the 100,000 year and 400,000 year eccentricity cycles. It is believed that this evidence for the eccentricity cycles in the dust record of the Eastern Mediterranean indicates a stronger northward progression of the North African Monsoonal Front during times when the eccentricity and precession insolation maxima coincide. The modulating effect of eccentricity on the precession cycle has also been shown using a global fully coupled atmosphere–ocean–sea ice climate model.

Lag

One key issue with the Orbital Monsoon Hypothesis is that a detailed inspection of climate record indicates that there is a 1000 to 2000 year lag in the observed North African Monsoon maximum compared to the predicted maximum. This issue occurs because the Orbital Monsoon Hypothesis assumes that there is an instantaneous response by the climate system to changes in insolation from orbital forcing. However, there are a number of fixes for this problem. The most reasonable fix can be shown through a simple analog to today's climate. Currently the peak in solar radiation occurs on June 21, but the peak of the summer monsoon in North Africa occurs a month later in July. A one-month lag such as this should be represented by roughly a 1500 to 2000 year lag in the monsoonal circulation maximum, because a July insolation maximum in a 19,000 to 23,000 year precession cycle occurs roughly 1500 to 2000 years after the June insolation maximum. Two other possible explanations for the observed lag in the data have been put forward. The first suggest that the development of the monsoons in the subtropics is tempered by the slow melting of polar ice sheets. Thus the full strength of the monsoonal pattern is not observed until the polar ice sheets have become so small that their impact on the development of yearly monsoons is minimal. The second alternative solution proposes that relatively cool tropical oceans left over from glaciation may initially slow the development of monsoons globally, since colder oceans are less potent sources of moisture.

Supporting evidence

Sapropels

Sapropels are dark organic rich marine sediments that contain greater than 2% organic carbon by weight. In the Eastern Mediterranean layers of sapropels can be found in marine sediment cores that align with periods of maximum insolation in the precession cycle over Northern Africa. Such an alignment can be explained by a link to the North African Monsoon. During periods of high insolation the increased strength and northward progression of the North African Monsoonal Front causes very heavy rain along the upper and middle reaches of the Nile River basin. These rains then flow northward and are discharged into the Eastern Mediterranean, where the large influx of nutrient rich fresh water causes a steep vertical salinity gradient. As a result, thermohaline convection is shut off and the water column becomes stably stratified. Once this stable stratification occurs, bottom waters in the Eastern Mediterranean quickly become depleted in oxygen and the large influx of pelagic organic matter from the nutrient rich surface waters is preserved as sapropel formations. One of the key pieces of evidence linking the formation of sapropels to enhance discharge from the Nile River is the fact that they have occurred during both interglacial and glacial periods. Therefore, the formation of sapropels must be linked to fresh water discharge from the Nile River and not melt water from dissipating ice sheets.

Paleolakes

Evidence for the existence of large lakes in the Sahara can be found and interpreted from the geologic record. These lakes fill as the precession cycle approaches the insolation maximum and are then depleted as the precession cycle nears the insolation minimum. The largest of these paleolakes was Lake Megachad, which at its peak was 173 m deep and covered an area of roughly 400,000 km2. Today the remnants of this once massive lake are known as Lake Chad, which has a maximum depth of 11 m and an area of only 1,350 km2. Satellite imagery of the shorelines of ancient Lake Megachad reveal that the lake has existed under two distinctive wind regimes, one northeasterly and southwesterly. The northeasterly wind regime is consistent with today's wind patterns and is characteristic of weak monsoonal flow. Meanwhile, the southwesterly wind regime is characteristic of a stronger monsoonal flow.

Freshwater diatoms

Another key piece of evidence for a processional control on the North African Monsoon can be found in the deposits of freshwater diatoms in the tropical Atlantic. Ocean cores from the tropical Atlantic have been found to have distinct layers of the freshwater diatom Aulacoseira granulata, also known as Melosira granulata. These layers occur on a 23,000 year cycle that lags the maximum in precession insolation by roughly 5000 to 6000 years. To explain these cyclic freshwater diatom deposits we have to look inland at the Sahara region of Africa. Around the time of the insolation maximum in the precession cycle the North African Monsoon is at its strongest and the Sahara region becomes dominated by large monsoonal lakes. Then as time progress toward the insolation minima, these lakes begin to dry out due to weakening North African Monsoon. As the lakes dry up thin sediment deposits containing freshwater diatoms are exposed. Finally, when the prevailing northeasterly winds arrive during winter, the freshwater diatom deposits in the dried lake beds are picked up as dust and carried thousands of kilometers out into the tropical Atlantic. From this series of events the reason for 5000 to 6000-year delay in the freshwater diatom deposits is evident, since the North African Monsoon must become sufficiently weak before the monsoonal lakes in the Sahara begin to dry up and expose potential freshwater diatom sources. One key factor that must be noted with freshwater diatom deposits is species identification. For instance some ocean cores directly off the western coast of Africa show a mix of freshwater lake and river diatom species. So for a core to accurately represent the diatom cycle of the Sahara it must be recovered from a region of the tropical Atlantic that has sufficient distance from the coast such that the impacts of river outflows are minimized.

Eastern equatorial Atlantic upwelling

Observed variations in the strength of the eastern equatorial Atlantic upwelling zone can also be used to support a cycle of the North African Monsoon that is regulated by the precession cycle. When insolation in North Africa is at its peak during the precession cycle the easterly trade winds over the equatorial Atlantic are strongly diverted toward the Sahara. This diversion weakens the equatorial upwelling zone in the eastern equatorial Atlantic, resulting in warmer waters in the pelagic. On the other end of the spectrum when insolation in North Africa is at a minimum due to the precession cycle, the diversion of the easterly trade winds is relatively weak. Due to this the region of upwelling in the eastern equatorial Atlantic remains strong and the waters in the pelagic zone are cooler. The proof that this pattern of periodic weakening of the eastern equatorial Atlantic upwelling exists is found in deposits of surface dwelling planktic organisms in ocean sediment cores. Such cores show that the relative abundance of warm and cold water planktic species vary with a consistent beat of 23,000 years, matching the 23,000 year precession insolation cycle.

African Humid Period

Main article: African humid period

Climatology

The African Humid Period occurred between 14,800 and 5,500 years ago, and was the last occurrence of a "green Sahara". Conditions in the Sahara during the African Humid Period were dominated by a strong North African Monsoon, resulting in larger annual rainfall totals compared to today's conditions. With the increased rainfall, the vegetation patterns in North Africa were nothing like what we see today. The majority of the Sahara region for instance was characterized by expansive grasslands, also known as steppe. Meanwhile, the Sahel region south of the Sahara was mostly savanna. Today the Sahara region is mostly desert and the Sahel is characterized by savannah grasslands conditions. The African Humid Period was also characterized by a network of vast waterways in the Sahara, consisting of large lakes, rivers, and deltas. The four largest lakes were Lake Megachad, Lake Megafezzan, Ahnet-Mouydir Megalake, and Chotts Megalake. Large rivers in the region included the Senegal River, Nile River, Sahabi River, and Kufra River. These river and lake systems provided corridors that allowed many animal species, including humans, to expand their range across the Sahara.

Onset and termination

Geologic evidence from the beginning and end of the African Humid Period suggests that both the onset and termination of the African Humid Period were abrupt. In fact both events likely occurred on a timescale of decades to centuries. The onset and termination of the African Humid Period both occurred when the insolation cycle reached a value of roughly 4.2% higher than today. However, shifts in the insolation cycle are too gradual to cause abrupt climate transitions like those seen at the onset and termination of the African Humid Period all on their own. So to account for these rapid shifts in the climate of the Sahara, several nonlinear feedback mechanisms have been proposed. One of the most common sets of nonlinear feedback mechanisms considered, are vegetation-atmosphere interactions. Computer models looking at vegetation-atmosphere interactions and insolation across North Africa have shown the ability to simulate the rapid transitions between "green Sahara" and "desert Sahara" regimes. Thus the results from these models suggest the possible existence of a vegetation-insolation threshold, which if reached, allows the Sahara region to rapidly transition from "green Sahara" to "desert Sahara" and vice versa.
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Papyrus

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Papyrus
Papyrus (P. BM EA 10591 recto column IX, beginning of lines 13–17)

Papyrus (/pəˈpaɪrəs/ pə-PY-rəs) is a material similar to thick paper that was used in ancient times as a writing surface. It was made from the pith of the papyrus plant, Cyperus papyrus, a wetland sedge. Papyrus (plural: papyri or papyruses) can also refer to a document written on sheets of such material, joined side by side and rolled up into a scroll, an early form of a book.

An official letter on a papyrus of the 3rd century BCE

Papyrus was first known to have been used in Egypt (at least as far back as the First Dynasty), as the papyrus plant was once abundant across the Nile Delta. It was also used throughout the Mediterranean region. Apart from a writing material, ancient Egyptians employed papyrus in the construction of other artifacts, such as reed boats, mats, rope, sandals, and baskets.

History

A section of the Egyptian Book of the Dead written on papyrus

Papyrus was first manufactured in Egypt as far back as the fourth millennium BCE. The earliest archaeological evidence of papyrus was excavated in 2012 and 2013 at Wadi al-Jarf, an ancient Egyptian harbor located on the Red Sea coast. These documents, the Diary of Merer, date from c. 2560–2550 BCE (end of the reign of Khufu). The papyrus rolls describe the last years of building the Great Pyramid of Giza. In the first centuries BCE and CE, papyrus scrolls gained a rival as a writing surface in the form of parchment, which was prepared from animal skins. Sheets of parchment were folded to form quires from which book-form codices were fashioned. Early Christian writers soon adopted the codex form, and in the Greco-Roman world, it became common to cut sheets from papyrus rolls to form codices.

Roman portraiture fresco of a young man with a papyrus scroll, from Herculaneum, 1st century AD

Codices were an improvement on the papyrus scroll, as the papyrus was not pliable enough to fold without cracking and a long roll, or scroll, was required to create large-volume texts. Papyrus had the advantage of being relatively cheap and easy to produce, but it was fragile and susceptible to both moisture and excessive dryness. Unless the papyrus was of perfect quality, the writing surface was irregular, and the range of media that could be used was also limited.

Papyrus was replaced in Europe by the cheaper, locally produced products parchment and vellum, of significantly higher durability in moist climates, though Henri Pirenne's connection of its disappearance with the Muslim conquest of Egypt between 639 and 646 CE is contested. Its last appearance in the Merovingian chancery is with a document of 692, though it was known in Gaul until the middle of the following century. The latest certain dates for the use of papyrus are 1057 for a papal decree (typically conservative, all papal bulls were on papyrus until 1022), under Pope Victor II, and 1087 for an Arabic document. Its use in Egypt continued until it was replaced by less expensive paper introduced by the Islamic world who originally learned of it from the Chinese. By the 12th century, parchment and paper were in use in the Byzantine Empire, but papyrus was still an option.

Papyrus was made in several qualities and prices. Pliny the Elder and Isidore of Seville described six variations of papyrus which were sold in the Roman market of the day. These were graded by quality based on how fine, firm, white, and smooth the writing surface was. Grades ranged from the superfine Augustan, which was produced in sheets of 13 digits (10 inches) wide, to the least expensive and most coarse, measuring six digits (four inches) wide. Materials deemed unusable for writing or less than six digits were considered commercial quality and were pasted edge to edge to be used only for wrapping.

Until the middle of the 19th century, only some isolated documents written on papyrus were known, and museums simply showed them as curiosities. They did not contain literary works. The first modern discovery of papyri rolls was made at Herculaneum in 1752. Until then, the only papyri known had been a few surviving from medieval times. Scholarly investigations began with the Dutch historian Caspar Jacob Christiaan Reuvens (1793–1835). He wrote about the content of the Leyden papyrus, published in 1830. The first publication has been credited to the British scholar Charles Wycliffe Goodwin (1817–1878), who published for the Cambridge Antiquarian Society, one of the Papyri Graecae Magicae V, translated into English with commentary in 1853.

Etymology

The English word "papyrus" derives, via Latin, from Greek πάπυρος (papyros), a loanword of unknown (perhaps Pre-Greek) origin. Greek has a second word for it, βύβλος (byblos), said to derive from the name of the Phoenician city of Byblos. The Greek writer Theophrastus, who flourished during the 4th century BCE, uses papyros when referring to the plant used as a foodstuff and byblos for the same plant when used for nonfood products, such as cordage, basketry, or writing surfaces. The more specific term βίβλος biblos, which finds its way into English in such words as 'bibliography', 'bibliophile', and 'bible', refers to the inner bark of the papyrus plant. Papyrus is also the etymon of 'paper', a similar substance.

In the Egyptian language, papyrus was called wadj (w3ḏ), tjufy (ṯwfy), or djet (ḏt).

Documents written on papyrus

Bill of sale for a donkey, papyrus; 19.3 by 7.2 cm, MS Gr SM2223, Houghton Library, Harvard University

The word for the material papyrus is also used to designate documents written on sheets of it, often rolled up into scrolls. The plural for such documents is papyri. Historical papyri are given identifying names – generally the name of the discoverer, first owner or institution where they are kept – and numbered, such as "Papyrus Harris I". Often an abbreviated form is used, such as "pHarris I". These documents provide important information on ancient writings; they give us the only extant copy of Menander, the Egyptian Book of the Dead, Egyptian treatises on medicine (the Ebers Papyrus) and on surgery (the Edwin Smith papyrus), Egyptian mathematical treatises (the Rhind papyrus), and Egyptian folk tales (the Westcar Papyrus). When, in the 18th century, a library of ancient papyri was found in Herculaneum, ripples of expectation spread among the learned men of the time. However, since these papyri were badly charred, their unscrolling and deciphering is still going on today.

Manufacture and use

Men splitting papyrus, Tomb of Puyemré; Metropolitan Museum of Art
Different ways of cutting papyrus stem and making of papyrus sheet
Papyrus plants near Syracuse, Sicily
Papyrus Flower on white background

Papyrus is made from the stem of the papyrus plant, Cyperus papyrus. The outer rind is first removed, and the sticky fibrous inner pith is cut lengthwise into thin strips of about 40 cm (16 in) long. The strips are then placed side by side on a hard surface with their edges slightly overlapping, and then another layer of strips is laid on top at right angles. The strips may have been soaked in water long enough for decomposition to begin, perhaps increasing adhesion, but this is not certain. The two layers possibly were glued together. While still moist, the two layers are hammered together, mashing the layers into a single sheet. The sheet is then dried under pressure. After drying, the sheet is polished with a rounded object, possibly a stone, seashell, or round hardwood.

Sheets, or Mollema, could be cut to fit the obligatory size or glued together to create a longer roll. The point where the Mollema are joined with glue is called the kollesis. A wooden stick would be attached to the last sheet in a roll, making it easier to handle. To form the long strip scrolls required, a number of such sheets were united, placed so all the horizontal fibres parallel with the roll's length were on one side and all the vertical fibres on the other. Normally, texts were first written on the recto, the lines following the fibres, parallel to the long edges of the scroll. Secondarily, papyrus was often reused, writing across the fibres on the verso. Pliny the Elder describes the methods of preparing papyrus in his Naturalis Historia.

In a dry climate, like that of Egypt, papyrus is stable, formed as it is of highly rot-resistant cellulose, but storage in humid conditions can result in molds attacking and destroying the material. Library papyrus rolls were stored in wooden boxes and chests made in the form of statues. Papyrus scrolls were organized according to subject or author and identified with clay labels that specified their contents without having to unroll the scroll. In European conditions, papyrus seems to have lasted only a matter of decades; a 200-year-old papyrus was considered extraordinary. Imported papyrus once commonplace in Greece and Italy has since deteriorated beyond repair, but papyri are still being found in Egypt; extraordinary examples include the Elephantine papyri and the famous finds at Oxyrhynchus and Nag Hammadi. The Villa of the Papyri at Herculaneum, containing the library of Lucius Calpurnius Piso Caesoninus, Julius Caesar's father-in-law, was preserved by the eruption of Mount Vesuvius, but has only been partially excavated.

Sporadic attempts to revive the manufacture of papyrus have been made since the mid-18th century. Scottish explorer James Bruce experimented in the late 18th century with papyrus plants from Sudan, for papyrus had become extinct in Egypt. Also in the 18th century, Sicilian Saverio Landolina manufactured papyrus at Syracuse, where papyrus plants had continued to grow in the wild. During the 1920s, when Egyptologist Battiscombe Gunn lived in Maadi, outside Cairo, he experimented with the manufacture of papyrus, growing the plant in his garden. He beat the sliced papyrus stalks between two layers of linen, and produced successful examples of papyrus, one of which was exhibited in the Egyptian Museum in Cairo. The modern technique of papyrus production used in Egypt for the tourist trade was developed in 1962 by the Egyptian engineer Hassan Ragab using plants that had been reintroduced into Egypt in 1872 from France. Both Sicily and Egypt have centres of limited papyrus production.

Papyrus is still used by communities living in the vicinity of swamps, to the extent that rural householders derive up to 75% of their income from swamp goods. Particularly in East and Central Africa, people harvest papyrus, which is used to manufacture items that are sold or used locally. Examples include baskets, hats, fish traps, trays or winnowing mats, and floor mats. Papyrus is also used to make roofs, ceilings, rope, and fences. Although alternatives, such as eucalyptus, are increasingly available, papyrus is still used as fuel.

Collections of papyrus

The Heracles Papyrus

Papyrus art

Drawing of a greater bird of paradise on papyrus
Drawing of a greater bird of paradise and the papyrus plant

Other ancient writing materials:

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