Green Impact Sheffield
The University of Sheffield

7 March, 2014 12:27


March 7th, 2014 - Posted under: Green Impact 2012/13 - Leave a Comment

Evidence for climate change

For our final blog I thought I’d review the latest evidence for man-made climate change. This review and all the quotes and images are from the IPCC (international panel on climate change) Climate Change 2013: The Physical Science Basis document. The summary is available here; http://www.climatechange2013.org/images/report/WG1AR5_SPM_FINAL.pdf

THE PAST

“Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased”

Map of the observed surface temperature change from 1901 to 20127yITWyayb6ut5PCGxcOXpei5vK0HJaPTv1sRXY_GMDw9hj3akz-CgggAA61qSlNjHri2hz5TB3TQQk7bmR_4fialfsj5C_0l-EDlj6ZNsXZgQIViHPlK525GulVR7A

“The frequency or intensity of heavy precipitation events has likely increased in North America and Europe.”

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“Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent.”

“The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia (high confidence). Over the period 1901 to 2010, global mean sea level rose by 0.19 [0.17 to 0.21] m”bRLNo21esdTb2XR15TPW9lr7sN-MbfE05CrG87jpzWFL5mNjH7gVSo8FCF6_Ypsp6p3ACGF3dDsC8o7NRsVkC97BGYZrkexeKLUU8XuiK_eBGTFsI2sAAvEQ16sHxw

Global mean sea level relative to the 1900–1905 mean of the longest running dataset

So there is firm evidence that the recent changes in climate are unprecedented.

THE PRESENT

“Human influence on the climate system is clear. This is evident from the increasing greenhouse gas concentrations in the atmosphere, positive radiative forcing, observed warming, and understanding of the climate system.”

“Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes […]. It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.”

We are the cause of climate change. But that means we can change things, both for good or worse.

THE FUTURE

“Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.”

“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, although there may be regional exceptions”

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“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”

So things are going to get worse before they get better and that the changes that need to be made need to be substantial and sustained.

This is why Green Impact is important at the University; we, as a source of education, we should be at the forefront of educating people that our personal actions affect the environment, and that without change the environment may become unable to sustain life in the way it has for millennia.



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