gcc_human - ENVST 110 Global Climate Change (Human Caused)...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
ENVST 110 Global Climate Change (Human Caused) Page 1 of 14 Evidence of Human cause to climate change: New Scientist (26 myths about climate change): http://environment.newscientist.com/channel/earth/dn11462 The first thing to remember is that we cannot collect what is called empirical evidence to show a causal relationship between the industrial revolution and global warming. This is because to conduct an experiment we would need a control group and a treatment group. The treatment group would be the earth we have that has experienced the industrial revolution. The control group would be an earth that has not gone through the industrial revolution. That control earth does not exist. So, we must depend on the accumulation of evidence much like a criminal trial. If the weight of the evidence points to guilt then the jury (the scientists) conclude a guilty verdict that human activities have contributed to climate change. In 1995, the world's climate experts in the IPCC concluded for the first time in a cautious consensus, "The balance of evidence suggests that there is a discernible human influence on the global climate." In its 2001 assessment, the IPCC strengthened that conclusion considerably, saying, "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.” Dr. Robert Watson, then Chairman of the Intergovernmental Panel on Climate Change, said in 2001, " The overwhelming majority of scientific experts, whilst recognizing that scientific uncertainties exist, nonetheless believe that human-induced climate change is already occurring and that future change is inevitable." From the 4 th IPCC report: “The understanding of anthropogenic warming and cooling influences on climate has improved since the Third Assessment Report (TAR), leading to very high confidence (>90%) that the globally averaged net effect of human activities since 1750 has been one of warming, with a radiative forcing of +1.6 [+0.6 to +2.4] W m- 2. (see Figure SPM-2). {2.3. 6.5, 2.9}” How do Human Activities Contribute to Climate Change and How do They Compare with Natural Influences? –IPCC 4 th report. http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter2.pdf Human activities contribute to climate change by causing changes in Earth’s atmosphere in the amounts of greenhouse gases, aerosols (small particles), and cloudiness. The largest known contribution comes from the burning of fossil fuels, which releases carbon dioxide gas to the atmosphere. Greenhouse gases and aerosols affect climate by altering incoming solar radiation and outgoing infrared (thermal) radiation that are part of Earth’s energy balance. Changing the atmospheric abundance or properties of these gases and particles can lead to a warming or cooling of the climate system. Since the start of the industrial era (about 1750), the overall effect of human activities on climate has been a warming influence. The human impact on climate
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 14

gcc_human - ENVST 110 Global Climate Change (Human Caused)...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online