Indicators of climate change can be found by careful analysis of climate records. With the development of far more widespread monitoring on both land and sea and new technologies ranging from weather balloons to satellites these records have become increasingly rich during the 20th century
Using this 170 year old set of records - making careful adjustments for ways in which different techniques for measurement and localised effects like urbanisation - climate analysts have built a picture of how climate has changed.
The data establishes key indicators
- Global mean temperature over sea and land has increased significantly over the 20th century
- There's been a steady rise in sea levels due to both thermal expansion and ice melt from glaciers and ice caps
- temperatures in the high northern latitudes have risen significantly
- there has been a significant increase in the number of extreme weather events
James Hanson predicted that extreme weather events would be a feature of climate change as long ago as 1990. There's a useful Climate Progress piece on extreme weather discussing the drought in the SW of the USA and the mechanisms that drive it. There's now evidence to show the frequency of climate extremes and global warming are linked as this National Oceanic and Atmosphere Administration report on Mediterranean Droughts demonstrates. There are numerous links to papers supporting the view that extreme weather events are increasing in this link to the Skeptical Science web site. John Vidal writing in the Guardian catalogues events through 2013 in "2013, a year of increasing extreme weather events" - where, in a catalogue of dangerously high temperatures he describes temperatures in Australia getting so high that the Australian Bureau of Meteorology has been forced to add another colour band to it's temperature charts.
The US Geological Society climate visualisation map clearly shows the increases in temperature and clearly shows that the greatest increases are in the far north - but it also shows smaller increases in many areas where human existence is already marginal, including the Mediterranean basin, the Russian Steppes, the US Mid and S. West and Australia. These increases are a major cause for concern as they could tip the balance into an environment that could no longer support agriculture. One illustration of this is that high food prices over the last few years were partially due poor harvests caused by drought and the Russian Steppes - a long term increase in drought intensity in a major world grain supply area would compromise food supplies globally.
Concern about the impacts of climate change is growing in the scientific community - as reflected in this release by the American Geophysical Union - first drafted in 2007 but reaffirmed in 2013 which says
"Impacts harmful to society, including increased extremes of heat, precipitation, and coastal high water are currently being experienced, and are projected to increase. Other projected outcomes involve threats to public health, water availability, agricultural productivity (particularly in low‐latitude developing countries), and coastal infrastructure, though some benefits may be seen at some times and places. Biodiversity loss is expected to accelerate due to both climate change and acidification of the oceans, which is a direct result of increasing carbon dioxide levels."
and calls for urgent action to reduce anthropogenic carbon emissions.
On first glance the increase in carbon emissions seems tiny in the context of global carbon cycles - but while the flows of carbon and carbon stored in the world's oceans and the biosphere are vast they are in a long term equilibrium - it's true that they may change gradually over many thousands of years - but the carbon from human activity has increased concentrations of free carbon dioxide very very quickly - almost doubling in the last 100 years - and it's this rapid increase that represents a major cause for concern.
Looking at global emissions on this World Bank interactive emissions graph it's clear there is a huge disparity between emissions in the developed and the developing world and while, for example, India's emissions are rising rapidly per capita emissions a tiny fraction of the average European, who in turn create less than half the CO2 of the average US Citizen.
China is the big new boy on the carbon block - and has outstripped even the USA - becoming the world's largest carbon produced in 2005 with total emissions now racing ahead of the rest of the world. It looks like China has taken over from the USA as the world's carbon bogyman - but the underlying realities tell a different story. The Worldwatch Institute say that a third of China's emissions are driven by exports to the west - so the west's claims for a reduced carbon emissions are not as clear cut as we claim. George Monbiot writes -
"When the impact of the goods we buy from other nations is counted, our total greenhouse gases did not fall by 19% between 1990 and 2008. They rose by 20%. This is despite the replacement during that period of many of our coal-fired power stations with natural gas, which produces roughly half as much carbon dioxide for every unit of electricity. When our “consumption emissions”, rather than territorial emissions, are taken into account, our proud record turns into a story of dismal failure"
The story of China - who's per capita carbon is way below all but the most economic developed nation illustrates both the stranglehold the west has on resources and the huge impact our consumer based economy has on carbon emissions and thus our climate.
"Impacts harmful to society, including increased extremes of heat, precipitation, and coastal high water are currently being experienced, and are projected to increase. Other projected outcomes involve threats to public health, water availability, agricultural productivity (particularly in low‐latitude developing countries), and coastal infrastructure, though some benefits may be seen at some times and places. Biodiversity loss is expected to accelerate due to both climate change and acidification of the oceans, which is a direct result of increasing carbon dioxide levels."
and calls for urgent action to reduce anthropogenic carbon emissions.
Video showing spectacular change to CO2 over the last 500 million years
watch the timescale of the left hand graph change as CO2 levels rise
Looking at global emissions on this World Bank interactive emissions graph it's clear there is a huge disparity between emissions in the developed and the developing world and while, for example, India's emissions are rising rapidly per capita emissions a tiny fraction of the average European, who in turn create less than half the CO2 of the average US Citizen.
China is the big new boy on the carbon block - and has outstripped even the USA - becoming the world's largest carbon produced in 2005 with total emissions now racing ahead of the rest of the world. It looks like China has taken over from the USA as the world's carbon bogyman - but the underlying realities tell a different story. The Worldwatch Institute say that a third of China's emissions are driven by exports to the west - so the west's claims for a reduced carbon emissions are not as clear cut as we claim. George Monbiot writes -
"When the impact of the goods we buy from other nations is counted, our total greenhouse gases did not fall by 19% between 1990 and 2008. They rose by 20%. This is despite the replacement during that period of many of our coal-fired power stations with natural gas, which produces roughly half as much carbon dioxide for every unit of electricity. When our “consumption emissions”, rather than territorial emissions, are taken into account, our proud record turns into a story of dismal failure"
The story of China - who's per capita carbon is way below all but the most economic developed nation illustrates both the stranglehold the west has on resources and the huge impact our consumer based economy has on carbon emissions and thus our climate.
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