PAST TEMPERATURES
RECENT TEMPERATURES
FUTURE TEMPERATURES
PHYSICAL INDICATORS
IMPACTS
Sea Level Rises:
Below follow the other most significant impacts to geophysical, biological and social systems as drawn from a Wikipedia article on the effects of climate change:
GEOPHYSICAL SYSTEMS:
-Biogeochemical Cycles: Climate change can have an effect on the carbon cycle in an interactive feedback process; Unanimous agreement was found among the models that future climate change will reduce the efficiency of the land and ocean carbon cycle to absorb human-induced CO2.
-Gas Hydrates: Future warming at intermediate depths in the world's oceans, as predicted by climate models, will tend to destabilize gas hydrates resulting in the release of large quantities of methane
-Sea Ice: As the climate warms, snow cover and sea ice extent decrease.
-Glaciers: Warming temperatures lead to the melting of glaciers and ice sheets. IPCC found that, on average, mountain glaciers and snow cover had decreased in both the northern and southern hemispheres. This widespread decrease in glaciers and ice caps has contributed to observed sea level rise.
-Oceans: The role of the oceans in global warming is a complex one. The oceans serve as a sink for carbon dioxide, taking up much that would otherwise remain in the atmosphere, but increased levels of CO2 have led to ocean acidification. Furthermore, as the temperature of the oceans increases, they become less able to absorb excess CO2. Global warming is projected to have a number of effects on the oceans. Ongoing effects include rising sea levels due to thermal expansion and melting of glaciers and ice sheets, and warming of the ocean surface, leading to increased temperature stratification. Other possible effects include large-scale changes in ocean circulation
- Ocean Acidification: It is estimated that the oceans have absorbed around half of all CO2 generated by human activities since 1800 (118 ± 19 petagrams of carbon from 1800 to 1994). In water, CO2 becomes a weak carbonic acid, and the increase in the greenhouse gas since the Industrial Revolution has already lowered the average pH (the laboratory measure of acidity) of seawater by 0.1 units, to 8.2. Predicted emissions could lower the pH by a further 0.5 by 2100, to a level probably not seen for hundreds of millennia and, critically, at a rate of change probably 100 times greater than at any time over this period.
-Thermohaline Circulation: There is some speculation that global warming could, via a shutdown or slowdown of the thermohaline circulation, trigger localized cooling in the North Atlantic and lead to cooling, or lesser warming, in that region. This would affect in particular areas like Scandinavia and Britain that are warmed by the North Atlantic drift.
-Extreme Weather:
-In increase in global mean temperature of about 0 to 2 °C by 2100 relative to the 1990–2000
period would result in increased fire frequency and intensity in many areas.
-Increased areas will be affected by drought
-There will be increased intense tropical cyclone activity
-There will be increased incidences of extreme high sea level
BIOLOGICAL SYSTEMS:
-Hundreds of studies have documented responses of ecosystems, plants, and animals to the climate changes that have already occurred. For example, in the Northern Hemisphere, species are almost uniformly moving their ranges northward and up in elevation in search of cooler temperatures.
-By the year 2100, ecosystems will be exposed to atmospheric CO2 levels substantially higher than in the past 650,000 years, and global temperatures at least among the highest of those experienced in the past 740,000 years. Significant disruptions of ecosystems are projected to increase with future climate change. Examples of disruptions include disturbances such as fire, drought, pest infestation, invasion of species, storms, and coral bleaching events. The stresses caused by climate change, added to other stresses on ecological systems (e.g., land conversion, land degradation, harvesting, and pollution), threaten substantial damage to or complete loss of some unique ecosystems, and extinction of some critically endangered species.
-Climate change has been estimated to be a major driver of biodiversity loss in cool conifer forests, savannas, mediterranean-climate systems, tropical forests, in the Arctic tundra, and in coral reefs. In other ecosystems, land-use change may be a stronger driver of biodiversity loss at least in the near-term. Beyond the year 2050, climate change may be the major driver for biodiversity loss global
SOCIAL SYSTEMS:
-The impacts of climate change can be thought of in terms of sensitivity and vulnerability. "Sensitivity" is the degree to which a particular system or sector might be affected, positively or negatively, by climate change and/orclimate variability. "Vulnerability" is the degree to which a particular system or sector might be adversely affected by climate change.
-The sensitivity of human society to climate change varies. Sectors sensitive to climate change include water resources, coastal zones, human settlements, and human health. Industries sensitive to climate change include agriculture, fisheries, forestry, energy, construction, insurance, financial services, tourism, and recreation.
-General circulation models project that the future climate change will bring wetter coasts, drier mid-continent areas, and further sea level rise. Such changes could result in the gravest effects of climate change through sudden human migration. Millions might be displaced by shoreline erosions, river and coastal flooding, or severe drought.
-Migration related to climate change is likely to be predominantly from rural areas in developing countries to towns and cities. In the short term climate stress is likely to add incrementally to existing migration patterns rather than generating entirely new flows of people. It has been argued that environmental degradation, loss of access to resources (e.g., water resources), and resulting human migration could become a source of political and even military conflict.
ABRUPT OR IRREVERSIBLE CHANGES:
Physical, ecological and social systems may respond in an abrupt, non-linear or irregular way to climate change. This is as opposed to a smooth or regular response. A quantitative entity behaves "irregularly" when its dynamics are discontinuous (i.e., not smooth), nondifferentiable, unbounded, wildly varying, or otherwise ill-defined. Such behaviour is often termed "singular." Irregular behaviour in Earth systems may give rise to certain thresholds, which, when crossed, may lead to a large change in the system. Some singularities could potentially lead to severe impacts at regional or global scales.
PART OF THE FUTURE IS ALREADY HERE:
Climate change is already damaging global economy, report finds
Economic impact of global warming is costing the world more than $1.2 trillion a year, wiping 1.6% annually from global GDP
Bangladeshi villagers rebuild an embankment after cyclone Aila hit in 2009. Bangladesh faces total losses of about 3-4% of GDP due to climate change. Photograph: Munir Uz Zaman/AFP/Getty Images
Climate change is already contributing to the deaths of nearly 400,000 people a year and costing the world more than $1.2 trillion, wiping 1.6% annually from global GDP, according to a new study.
The impacts are being felt most keenly in developing countries, according to the research, where damage to agricultural production from extreme weather linked to climate change is contributing to deaths from malnutrition, poverty and their associated diseases.
Air pollution caused by the use of fossil fuels is also separately contributing to the deaths of at least 4.5m people a year, the report found.
The 331-page study, entitled Climate Vulnerability Monitor: A Guide to the Cold Calculus of A Hot Planet and published on Wednesday, was carried out by the DARA group, a non-governmental organisation based in Europe, and the Climate Vulnerable Forum. It was written by more than 50 scientists, economists and policy experts, and commissioned by 20 governments.
By 2030, the researchers estimate, the cost of climate change and air pollution combined will rise to 3.2% of global GDP, with the world's least developed countries forecast to bear the brunt, suffering losses of up to 11% of their GDP.
Sheikh Hasina, prime minister of Bangladesh, said: "A 1C rise in temperature [temperatures have already risen by 0.7C globally since the end of the 19th century] is associated with 10% productivity loss infarming. For us, it means losing about 4m tonnes of food grain, amounting to about $2.5bn. That is about 2% of our GDP. Adding up the damages to property and other losses, we are faced with a total loss of about 3-4% of GDP. Without these losses, we could have easily secured much higher growth."
But major economies will also take a hit, as extremes of weather and the associated damage – droughts, floods and more severe storms – could wipe 2% of the GDP of the US by 2030, while similar effects could cost China $1.2tr by the same date.
While many governments have taken the view that climate change is a long-term problem, there is a growing body of opinion that the effects are already being felt. Scientists have been alarmed by the increasingly rapid melting of Arctic sea ice, which reached a new record minimum this year and, if melting continues at similar rates, could be ice free in summer by the end of the decade. Some research suggests that this melting could be linked to cold, dull and rainy summers in parts of Europe – such as has been the predominant summer weather in the UK for the last six years. In the US, this year's severe drought has raised food prices and in India the disruption to the monsoon has caused widespread damage to farmers.
Connie Hedegaard, the European Union's climate chief, warned that extreme weather was becoming more common, as the effects of climate change take hold. "Climate change and weather extremes are not about a distant future," she wrote in a comment for the Guardian last week. "Formerly one-off extreme weather episodes seem to be becoming the new normal."
Michael Zammit Cutajar, former executive secretary of the UN Framework Convention on Climate Change, said: "Climate change is not just a distant threat but a present danger – its economic impact is already with us."
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