Query: We note that the Earth has never in its history had a quasi-stable state that is around 2C warmer than the preindustrial and suggest that there is substantial risk that the system, itself, will ‘want’ to continue warming because of all of these other processes – even if we stop emissions,” she said.

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Planetary boundaries <=SEP=> Planetary boundaries is the central concept in an Earth system framework proposed by a group of Earth system and environmental scientists led by Johan Rockström from the Stockholm Resilience Centre and Will Steffen from the Australian National University . In 2009 , the group proposed a framework of `` planetary boundaries '' designed to define a `` safe operating space for humanity '' for the international community , including governments at all levels , international organizations , civil society , the scientific community and the private sector , as a precondition for sustainable development . This framework is based on scientific research that indicates that since the Industrial Revolution , human actions have gradually become the main driver of global environmental change . The scientists assert that once human activity has passed certain thresholds or tipping points , defined as `` planetary boundaries '' , there is a risk of `` irreversible and abrupt environmental change '' . The group identified nine Earth system processes which have boundaries that , to the extent that they are not crossed , mark the safe zone for the planet . However , because of human activities some of these dangerous boundaries have already been crossed , while others are in imminent danger of being crossed .   Rockström and Steffen collaborated with 26 leading academics , including Nobel laureate Paul Crutzen , Goddard Institute for Space Studies climate scientist James Hansen and the German Chancellor 's chief climate adviser Hans Joachim Schellnhuber . The group identified nine `` planetary life support systems '' essential for human survival , and attempted to quantify just how far seven of these systems have been pushed already . They then estimated how much further we can go before our own survival is threatened ; beyond these boundaries there is a risk of `` irreversible and abrupt environmental change '' which could make Earth less habitable . Estimates indicate that three of these boundaries -- climate change , biodiversity loss , and the biogeochemical flow boundary -- appear to have been crossed . The boundaries are `` rough , first estimates only , surrounded by large uncertainties and knowledge gaps '' that interact in ways that are complex and not well understood . Boundaries can help identify where there is room and define a `` safe space for human development '' , which is an improvement on approaches which aim at just minimizing human impacts on the planet . The 2009 report was presented to the General Assembly of the Club of Rome in Amsterdam . An edited summary of the report was subsequently published as the featured article in a special edition of Nature . Nature also published critical commentary from leading academics they invited to comment on each of the seven planetary boundaries which had been quantified , including comments from Nobel laureate Mario J. Molina and biologist Cristián Samper . In 2015 , a second paper was published in Science updating the Planetary Boundaries concept . The findings were presented at the World Economic Forum in Davos , January 2015 .

Global warming <=SEP=> Global warming , also referred to as climate change , is the observed century-scale rise in the average temperature of the Earth 's climate system and its related effects . Multiple lines of scientific evidence show that the climate system is warming . Many of the observed changes since the 1950s are unprecedented in the instrumental temperature record which extends back to the mid 19th century , and in paleoclimate proxy records over thousands of years .   In 2013 , the Intergovernmental Panel on Climate Change ( IPCC ) Fifth Assessment Report concluded that `` It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century . '' The largest human influence has been emission of greenhouse gases such as carbon dioxide , methane and nitrous oxide . Climate model projections summarized in the report indicated that during the 21st century the global surface temperature is likely to rise a further 0.3 to for their lowest emissions scenario and 2.6 to for the highest emissions scenario . These findings have been recognized by the national science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing .   Future climate change and associated impacts will differ from region to region around the globe . Anticipated effects include warming global temperature , rising sea levels , changing precipitation , and expansion of deserts in the subtropics . Warming is expected to be greater over land than over the oceans and greatest in the Arctic , with the continuing retreat of glaciers , permafrost and sea ice . Other likely changes include more frequent extreme weather events including heat waves , droughts , heavy rainfall with floods and heavy snowfall ; ocean acidification ; and species extinctions due to shifting temperature regimes . Effects significant to humans include the threat to food security from decreasing crop yields and the abandonment of populated areas due to rising sea levels . Because the climate system has a large `` inertia '' and greenhouse gases will stay in the atmosphere for a long time , many of these effects will not only exist for decades or centuries , but will persist for tens of thousands of years .   Possible societal responses to global warming include mitigation by emissions reduction , adaptation to its effects , building systems resilient to its effects , and possible future climate engineering . Most countries are parties to the United Nations Framework Convention on Climate Change ( UNFCCC ) ,  whose ultimate objective is to prevent dangerous anthropogenic climate change . Parties to the UNFCCC have agreed that deep cuts in emissions are required and that global warming should be limited to well below 2.0 C-change relative to pre-industrial levels , with efforts made to limit warming to 1.5 C-change .   Public reactions to global warming and concern about its effects are also increasing . A global 2015 Pew Research Center report showed a median of 54 % consider it `` a very serious problem '' . There are significant regional differences , with Americans and Chinese ( whose economies are responsible for the greatest annual CO2 emissions ) among the least concerned .