Historic evidence reveals secret of the “Climate sensitivity” in the atmosphereMd Noman Siddique (Author) Published Date : Feb 05, 2015 13:40 IST
The Pliocene, the Earth s latest warm period has been studied by a group of multinational researchers and they have stated that the recent forecasts on climatic change from the IPCC are right.
Pliocene happened approximately 2.3 to 3.3 million years ago the carbon dioxide in the atmosphere was 350-400 PPM, a point which reached in 2014. The planet was 3.5 F (2 C) compared to the current condition.
Researchers were able to predict the way the climatic condition will react to the rise in carbon dioxide level in this current situation or the climate sensitivity. As published in Nature, this study also observes the way climate sensitivity can fluctuate in the long haul.
We can understand that CO2 does not correlate to temperature right away. The atmospheric carbon dioxide took a level of 400 ppm although that will take a while for the warming to take place. Greenhouse gases bring in warmth by fencing in heat. The heat of the sun is responsible for warmth but with a low level of carbon dioxide a huge portion of it vanishes in space. The increase in the amount of greenhouse gases eventually leads to warmer average temperature.
Gavin Foster, a co-author of the study from University of Southampton said that Today the Earth is still adjusting to the recent rapid rise of CO2 caused by human activities, whereas the longer-term Pliocene records document the full response of CO2-related warming. Our estimates of climate sensitivity lie well within the range of 1.5 to 4.5 C increase per CO2 doubling summarized in the latest IPCC report. This suggests that the research community has a sound understanding of what the climate will be like as we move toward a Pliocene-like warmer future caused by human greenhouse gas emissions.
Our new records also reveal an important change at around 2.8 million years ago, when levels rapidly dropped to values of about 280 ppm, similar to those seen before the industrial revolution. This caused a dramatic global cooling that initiated the ice-age cycles that have dominated Earth s climate ever since, said lead author Dr Miguel Mart nez-Bot , also from Southampton.
The researchers said that the affect of the current level of CO2 has the possibility of being felt for centuries along with a rise in sea level starting from 30 to 100 feet.
Over the next several centuries, ice sheets could be expected to return to Pliocene levels, said Professor Eelco Rohling from the Research School of Earth Sciences at Australian National University, a co-author of the paper said.
Rohling also said that even though the temperature and sea level are just starting to change, the ice cover has already started to adapt to this climate. It is West Antarctica and Greenland that are most important and they can be responsible for 12m of sea level. Processes are just getting going.
The group has also observed if the climate sensitivity altered over time.
We find that climate change in response to CO2 change in the warmer period was around half that of the colder period. We determine that this difference is driven by the growth and retreat of large continental ice sheets that are present in the cold ice-age climates; these ice sheets reflect a lot of sunlight and their growth consequently amplifies the impact of CO2 changes, Professor Eelco Rohling of The Australian National University in Canberra.
When we account for the influence of the ice sheets, we confirm that the Earth s climate changed with a similar sensitivity to overall forcing during both warmer and colder climates, added Professor Richard Pancost from the University of Bristol Cabot Institute.
The recent volcanic activity is considered to have reduced the recent impacts of the change and a study published in Nature Geoscience says that volcanoes are to some extent accountable for a the alleged global warming hiatus Volcanoes give out massive amounts of CO2 which is what causes the problem.
Nonetheless, in the short-run they can have a cooling effect. Volcanoes also emits sulfur dioxide into the stratosphere and later the gas turns onto small dewdrops of sulfuric acid, the reason behind acid rain that mirrors the light coming in to the Earth back to space and with less light reaching the Earth, the atmosphere cools momentarily.
Historic evidence reveals secret of the “Climate sensitivity” in the atmosphere