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Does atmospheric CO2 cause significant global warming?

In 1896 Svante Arrhenius modeled the greenhouse effect, where gases in the atmosphere such as CO2 trap sunlight much like glass traps heat in a greenhouse. His principle is foundational in climatology, though today we have a more refined understanding of physical chemistry and we use Global Climate Models to predict that an increase in CO2 will actually result in global warming.

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Experts and Influencers

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Agree
Experts In Climatology


Intergovernmental Panel on Climate Change    (IPCC) Scientific Body formed by U.N.
Agree
Palaeoclimate model simulations are broadly consistent with the reconstructed Northern Hemisphere temperatures over the past 1000 years. The rise in surface temperatures since 1950 very likely cannot be reproduced without including anthropogenic greenhouse gases in the model forcings, and it is very unlikely that this warming was merely a recovery from a pre-20th century cold period.
01 Jan 2008    Source


Gavin Schmidt    Climatologist
Agree
We often get requests to provide an easy-to-understand explanation for why increasing CO2 is a significant problem without relying on climate models and we are generally happy to oblige. The explanation has a number of separate steps which tend to sometimes get confused and so we will try to break it down carefully.
06 Aug 2007    Source


Experts In Science


Svante Arrhenius    Scientist, First Modeled Greenhouse Effect
Agree
A simple calculation shows that the temperature in the arctic regions would rise about 8° to 9°C., if the carbonic acid increased to 2.5 or 3 times its present value.
01 Apr 1896    Source


Disagree
Experts In Science


Denis Rancourt    Physics Professor
Mostly Disagree
CO2 increases may accompany temperature increases rather than causing them. Indeed, some high resolution studies have suggested that the temperature increases precede the CO2 increases. Interestingly, also, ice core data shows strong temporal correlations between inferred temp. and amount of dust preserved in the ice core. Finally, the older geological record shows several dramatic examples of where CO2 concentration and global average temperature were either unrelated or even anti-correlated.
27 Feb 2007    Source

Sub-Arguments Of This Expert:
Has CO2 passively lagged temperature in past climates?
   Agree

Qing-Bin Lu    Physics Professor
Mostly Disagree
This study did not aim to make precise calculations of global temperature change with a sophisticated climate model including multiple parameters and factors. But it does show that the warming effect of CO2 was not the main cause of these climate transitions and other non-CFC gases had most likely saturated and CFCs and HCFCs could account for global warming observed in the late 20th century. A long-term global cooling starting around 2002 is expected to continue for next five to seven decades.
01 Jun 2010    Source


Syun-Ichi Akasofu    Geophysics Professor
Disagree
If you look back far enough, we have a bunch of data that show that warming has gone on from the 1600s with an almost linear increase to the present.
01 Apr 2007    Source


Gerhard Gerlich    Physics Professor
Disagree
There is no atmospheric greenhouse effect, in particular CO2-greenhouse effect, in theoretical physics and engineering thermodynamics. Thus it is illegitimate to deduce predictions which provide a consulting solution for economics and intergovernmental policy.
07 Jul 2007    Source



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1 Point      DGwartney      08 May 2009      Stance on Question: Agree
Positive and negative feedbacks on the climate are basically used to define the stability of a given climate. Positive feedbacks are those that directly impact the earth’s climate system which can cause a change in climate to occur, leading to even further change in the climate. A negative feedback is one that may cause a climate change, but effectively leads to further mechanisms that act as mitigation towards negative impacts that can emerge from environmental change.

A very strong example of a positive feedback mechanism is ocean warming. This is a very important topic that many researchers have been studying for quite some time. This is a positive feedback due to the ability of water to act as a sink for CO2. The oceans are great sources for absorbing CO2 from the atmosphere which is beneficial to cooling the atmosphere. However, as air temperature increases (possibly from excess CO2 emissions) oceans will increase in temperature and will be less dense, thus losing their ability to absorb excess CO2 from the atmosphere. Due to this, increasing CO2 in the atmosphere will continue to increase air temperature, which in turn increases ocean surface temperature.

A negative feedback would be if increasing temperature leads to increasing evapotranspiration. Effectively, this would have the possibility to increase cloud cover in the atmosphere. This may be advantageous in the ability of the clouds to reflect incident solar radiation, thus leading to cooler temperatures. There is a caveat to this though; if the increase in clouds are low they will indeed cool, but if the clouds produced act as cirrus (very high) they would have the ability to increase temperature. This falls in the category of possibly increasing the greenhouse effect with increasing cirrus formation.