Query: This could mean the landmark Paris Climate Agreement – which seeks to limit global warming to 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels – may not be enough to ward off catastrophe.

Relevant passages:
Paris Agreement <=SEP=> The Paris Agreement ( Accord de Paris ) is an agreement within the United Nations Framework Convention on Climate Change ( UNFCCC ) dealing with greenhouse gas emissions mitigation , adaptation and finance starting in the year 2020 . The language of the agreement was negotiated by representatives of 195 countries at the 21st Conference of the Parties of the UNFCCC in Paris and adopted by consensus on 12 December 2015 . It was opened for signature on 22 April 2016 ( Earth Day ) at a ceremony in New York . As of May 2017 , 195 UNFCCC members have signed the treaty , 147 of which have ratified it . After several European Union states ratified the agreement in October 2016 , there were enough countries that had ratified the agreement that produce enough of the world 's greenhouse gases for the agreement to enter into force . The agreement went into effect on 4 November 2016 .   The head of the Paris Conference , France 's foreign minister Laurent Fabius , said this `` ambitious and balanced '' plan is a `` historic turning point '' in the goal of reducing global warming .   One year on , the ratification of the Paris Agreement was celebrated by the Mayor of Paris Anne Hidalgo by illuminating the Eiffel Tower and the Arc de Triomphe , Paris ' most iconic monuments , in green .

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 .