Final Exam (Geography) 3
The warming occurred in two distinct periods
(1910-1940) and from 1975 to 2000.
Tropospheric aerosols are formed by
- dispersal of material from the surface, for example dust, - direct emission of material into the atmosphere, for example, smoke, - chemical reactions in the atmosphere which convert gases, such as sulphur dioxide, into particles.
Measurement indicate that Methane concentration has increased from a pre-industrial level of about
0.75 ppm to about 1.8 ppm in 2012 (an increase of about 1 ppm)
Warming of about 0.6 C results from
1 W/m2 forcing
whats happening to the glaciers?
All survey regions except Scandinavia show a net thinning. During this period, 83% of surveyed glaciers showed thinning with an average loss across all glaciers of 0.31 m/yr. The most rapidly shrinking was Ivory glacier in New Zealand which was thinning at 2.4 m/yr. Ivory glacier had totally disintegrated by circa 1988.
whats happening to different ecosystems?
Approximately 20-30% of plant and animal species assessed so far are likely to be at increased risk of extinction if increases in global average temperature exceed 1.5 to 2.5C.
how does aerosol concentration affect the amount of sun that is reflected to space?
As aerosol concentration increases within a cloud, the water in the cloud gets spread over many more particles, each of which is correspondingly smaller. Clouds with smaller drops reflect more sunlight, and such clouds last longer, because it takes more time for small drops to coalesce into drops that are large enough to fall to the ground. This increases the amount of sunlight that is reflected to space without reaching the surface.
how are water resources changing?
By mid-century, annual average river runoff and water availability are projected to increase by 10-40% at high latitudes and in some wet tropical areas, and decrease by 10-30% over some dry regions at mid-latitudes and in the dry tropics, some of which are presently water stressed areas. Drought-affected areas will likely increase in extent. Heavy precipitation events, which are very likely to increase in frequency, will augment flood risk.
whats happening in latin america?
By mid-century, increases in temperature and associated decreases in soil water are projected to lead to gradual replacement of tropical forest by savanna in eastern Amazonia. Semi-arid vegetation will tend to be replaced by arid-land vegetation. There is a risk of significant biodiversity loss through species extinction in many areas of tropical Latin America. Productivity of some important crops are projected to decrease and livestock productivity to decline, with adverse consequences for food security.
Thus, the present estimate for global warming is about
1.37C
by how much will the temperature increase by end of 21st century and how much will the sea level increase?
2 degrees C; .5m
The total anthropogenic radiative forcing is estimated to be
2.29 W/m2
Over the last 400,000 years, CO2 concentration was less than
280 ppmv
This graph depicts the decline in arctic summer sea ice extent from 1979-2012 - a decline of more than _ percent per decade. The arctic could be ice-free by _ - even earlier than the prediction of IPCC
8 2060
net radiation =
Absorbed Solar Radiation - Outgoing Longwave Radiation
what is the indirect effect of aerosols on climate?
Aerosols are also believed to have an "indirect" effect on climate by changing properties of clouds. Indeed, if there were no aerosols in the atmosphere, there would be no clouds. It is very difficult to form clouds without small aerosol particles acting as "seeds" to start the formation of cloud droplets.
what are aerosols?
Aerosols are suspensions of particles in the atmosphere, with diameters in the range 10^-3 to 10^-6 meters
what is the direct effect of aerosols?
Aerosols tend to cause cooling of the Earth's surface immediately below them. Because most aerosols reflect sunlight back into space, they have a "direct" cooling effect by reducing the amount of solar radiation that reaches the surface. It is thought that aerosol cooling may partially offset expected global warming that is attributed to increases in the amount of carbon dioxide from human activity.
whats happening in africa?
Agricultural production, including access to food, in many African countries and regions is projected to be severely compromised by climate variability and change. The area suitable for agriculture, the length of growing seasons and yield potential, particularly along the margins of semi-arid and arid areas, are expected to decrease. In some countries, yields from rain-fed agriculture could be reduced by up to 50% by 2020.
whats happening in asia?
Coastal areas, especially heavily-populated mega-delta regions in South, East and Southeast Asia, will be at greatest risk due to increased flooding from the sea and in some mega-deltas flooding from the rivers.
whats happening at the coasts?
Coasts are projected to be exposed to increasing risks, including coastal erosion, due to climate change and sea-level rise and the effect will be exacerbated by increasing human-induced pressures on coastal areas. Corals are vulnerable to thermal stress and have low adaptive capacity. Increases in sea surface temperature of about 1 to 3°C are projected to result in more frequent coral bleaching events and widespread mortality, unless there is thermal adaptation or acclimatization by corals. Coastal wetlands including salt marshes and mangroves are projected to be negatively affected by sea-level rise especially where they are constrained on their landward side, or starved of sediment.
whats happening with crops?
Crop productivity is projected to increase slightly at mid to high latitudes for local mean temperature increases of up to 1-3°C depending on the crop, and then decrease beyond that in some regions. At lower latitudes, especially seasonally dry and tropical regions, crop productivity is projected to decrease for even small local temperature
some depressing facts about climate:
Global surface temperature change for the end of the 21st century is likely to exceed 1.5°C relative to 1850 to 1900 for all RCP scenarios except RCP2.6. Warming will not be regionally uniform. Changes in the global water cycle in response to the warming over the 21st century will not be uniform. The contrast in precipitation between wet and dry regions and between wet and dry seasons will increase. The global ocean will continue to warm during the 21st century. Heat will penetrate from the surface to the deep ocean and affect ocean circulation. It is very likely that the Arctic sea ice cover will continue to shrink and thin and that Northern Hemisphere spring snow cover will decrease during the 21st century as global mean surface temperature rises. Global glacier volume will further decrease. Global mean sea level will continue to rise during the 21st century. Under all RCP scenarios, the rate of sea level rise will very likely exceed that observed during 1971 to 2010 due to increased ocean warming and increased loss of mass from glaciers and ice sheets. Climate change will affect carbon cycle processes in a way that will exacerbate the increase of CO2 in the atmosphere (high confidence). Further uptake of carbon by the ocean will increase ocean acidification. Cumulative emissions of CO2 largely determine global mean surface warming by the late 21st century and beyond. Most aspects of climate change will persist for many centuries even if emissions of CO2 are stopped. This represents a substantial multi-century climate change commitment created by past, present and future emissions of CO2.
whats happening in the polar regions?
In the Polar Regions, the main projected biophysical effects are reductions in thickness and extent of glaciers and ice sheets, and changes in natural ecosystems with detrimental effects on many organisms including migratory birds, mammals and higher predators. In the Arctic, additional impacts include reductions in the extent of sea ice and permafrost, increased coastal erosion, and an increase in the depth of permafrost seasonal thawing. For Arctic human communities, impacts, particularly resulting from changing snow and ice conditions, are projected to be mixed. Detrimental impacts would include those on infrastructure and traditional indigenous ways of life.
what resulted from an Increase in CO2 concentration from the pre-industrial (year 1750) period to the early 2010s?
Increase in CO2 concentration from the pre-industrial (year 1750) period to early 2010s has resulted in a positive radiative forcing of the climatic system of about 1.68 W/m2
what is the pattern of precipitation change? aka where is it increasing and decreasing by latitudes
Large increases in the high latitudes Moderate increases in the mid latitudes Declines in the subtropics
has the climate gotten wetter? if yes, where? if no, where?
Mid and High Latitudes: During the 20th Century, annual-zonally averaged precipitation increased between 9% and 16% for the zones 30N to 85N and by about 2 to 5% between 0S to 55S during this time Tropics and Sub-Tropics: The increase of precipitation in the middle and high latitudes contrasts with decreases in the northern subtropics.
Over ________, warming is seen everywhere except south of Greenland and in a few scattered continental regions in the tropics or subtropics.
Over 1880-2007
if net radiation (Rn) is is positive then _ happens and there is an increase in
Sn (absorbed solar radiation) is greater than Lu (Outgoing LW Rad), results in WARMING (Greenhouse Gases)
if net radiation (Rn) is negative then _ happens and there is an increase in
Sn (absorbed solar radiation) is lesser than Lu (Outgoing LW Rad), results in COOLING (aerosols) (increase in clouds)
What is IPCC?
The Intergovernmental Panel on Climate Change (IPCC) is a United Nations body, founded in 1988, which evaluates climate change science. The IPCC assesses research on climate change and synthesises it into major assessment' reports every 5-7 years.
The mauna loa observatory notes what affects the amount of CO2 present?
The annual cycle in the Mauna Loa record is due to the seasonality of vegetation. In early spring, the concentration of CO2 is at its maximum, and as the plants green-up, the concentration drops, reaching a minimum value towards the end of the summer, and when it starts to build up again. This swing in the amplitude is most pronounced in the records from the northern high latitudes, where it can be as large as 15 ppmv.
whats happening in the oceans?
The progressive acidification of oceans due to increasing atmospheric carbon dioxide is expected to have negative impacts on marine shell forming organisms (e.g., corals) and their dependent species.
what are the main anthropogenic sources of aerosols?
The release of sulphur dioxide from fossil fuel combustion and biomass burning
The increase in methane since pre-industrial times is estimated to have resulted in
a radiative forcing of about 1 W/m2, which is quite significant when compared to the increase in carbon dioxide concentration during the same time period and its radiative forcing (1.7 Watts/m2). Thus, methane is a very powerful greenhouse gas.
In Spring 2015, CO2 concentration was
about 400 ppmv
The atmospheric CO2 record prior to 1957 comes mainly from?
air bubbles in ice cores
where are the most vulnerable industries, settlements and societies?
coastal and river flood plains, those whose economies are closely linked with climate-sensitive resources, and those in areas prone to extreme weather events, especially where rapid urbanization is occurring. Poor communities can be especially vulnerable, in particular those concentrated in high-risk areas. They tend to have more limited adaptive capacities, and are more dependent on climate- sensitive resources such as local water and food supplies.
The growth rate of Methane has been ___ since the mid 80s for reasons not well understood.
decreasing
If conclusions regarding trends cannot always be drawn, it (does/ does not )necessarily mean that the trends are absent!
does not It is possible that the data quality hinders such analyses!
why is the sea level rising
due to thermal expansion and melting ice sheets
Continued emissions of ___ will cause further warming and changes in all components of the climate system. Limiting climate change will require __________?
greenhouse gases; substantial and sustained reductions of greenhouse gas emissions.
A further 0.97 W/m2 forcing has resulted from ____ during the same period
increase in methane concentration
Methane (CH4) is another naturally occurring greenhouse gas whose concentration in the atmosphere has been __ as a result these of human activities
increasing; - rice paddies - animal husbandry - landfills - biomass burning - fossil fuel production
The __ in atmospheric CO2 concentration is growing in parallel with CO2 emissions.
inter-hemispheric gradient
The total radiative forcing due to green house gases (GHG) in W/m^2
is estimated to be about 3 W/m2
should you focus on the global annual mean surface temp?
no; it could be misleading For example, in some regions the warming could be as much 5C or even 10C Warming is greater on land than on oceans Warming is greater in the high latitudes than in the tropics Clearly, the magnitude of warming depends on the future anthropogenic forcings
is methane a weak or powerful greenhouse gas
powerful
climate models reproduce observed temperature evolution only when both natural and anthropogenic forcings are used - which suggests ...
that the observed 20th century warming is not natural.
The rise in atmospheric CO2 concentration closely follows which increase in emissions
the increase in emissions related to fossil fuel burning.
fact: As predicted by greenhouse theory, cooling of the lower stratosphere and warming of the lower troposphere are observed in both satellite and radiosonde data. The lower troposphere warming is also consistent with observations of surface warming, but some discrepancy prior to 1980s should be noted.
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lots of images that you need from lecture 27
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the 20th century increase in CO2 conc is unparalleled in the past 400,000 years
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has the climate warmed?
· Global surface temperatures have increased by about 0.8C since the late 19th century, but most of this increase has occurred in two distinct periods, 1910-40 and since mid-1970s. · The rate of temperature increase since 1980 has been 0.2C per decade. · Largest rates of warming continue to be found in the middle and high latitude continental regions of the Northern Hemisphere. · Analyses of overall temperature trends in the low to mid troposphere and near the surface since 1958 are in good agreement, with a warming of about 0.1C per decade. · Changes in Northern Hemisphere snow cover extent, sea ice extent and glacier retreat are consistent with temperature increases over the past 100 odd years.
what are the health effects of climate change?
• increases in malnutrition and consequent disorders, with implications for child growth and development; • increased deaths, disease and injury due to heat waves, floods, storms, fires and droughts; • the increased burden of diarrhoeal disease; • the increased frequency of cardio-respiratory diseases due to higher concentrations of ground level ozone related to climate change; and, • the altered spatial distribution of some infectious disease vectors (malaria).
