Query: […] in fact this pattern is already emerging, with the conditions that create extremely warm dry years and extremely wet years both becoming more frequent.

Relevant passages:
List of ecoregions in North America (CEC) <=SEP=> This list of ecoregions of North America provides an overview of North American ecoregions designated by the Commission for Environmental Cooperation ( CEC ) in its North American Environmental Atlas . It should not be confused with Wikipedia articles based on the classification system developed by the World Wildlife Fund , such as List of ecoregions ( WWF ) and Lists of ecoregions by country .   The commission was established in 1994 by the member states of Canada , Mexico , and the United States to address regional environmental concerns under the North American Agreement on Environmental Cooperation ( NAAEC ) , the environmental side accord to the North American Free Trade Agreement ( NAFTA ) . The Commission 's 1997 report , Ecological Regions of North America , provides a framework that may be used by government agencies , non-governmental organizations , and academic researchers as a basis for risk analysis , resource management , and environmental study of the continent 's ecosystems . Ecoregions may be identified by similarities in geology , physiography , vegetation , climate soils , land use , wildlife distributions , and hydrology .   The classification system has four levels . Only the first three levels are shown on this list . `` Level I '' divides North America into 15 broad ecoregions . `` Level II '' subdivides the continent into 52 smaller ecoregions . `` Level III '' subdivides those regions again into 182 ecoregions . `` Level IV '' is a further subdivision of Level III ecoregions . Level IV mapping is still underway but is complete across most of the United States . For an example of Level IV data , see List of ecoregions in Oregon and the associated articles .

Alentejo <=SEP=> Alentejo is a geographical , historical and cultural region of south-central and southern Portugal . Literally , in Portuguese it means `` beyond '' ( além ) Tagus river ( Tejo ) .   Alentejo includes the regions of Alto Alentejo and Baixo Alentejo . It corresponds to the districts of Beja , Évora , Portalegre and the Alentejo Litoral . The main cities are : Évora , Beja , Serpa , Estremoz , Elvas and Portalegre .   It has borders with Beira Baixa in the North , with Spain ( Andalucia and Extremadura in the east , with Algarve in the South and with the Atlantic Ocean , Ribatejo and Estremadura in the West .   The Alentejo is a region known for its traditional polyphonic singing groups , similar to those found in Tuscany , Corsica , and elsewhere .

Temperate climate <=SEP=> In geography , temperate or tepid latitudes of Earth lie between the tropics and the polar regions . The temperatures in these regions are generally relatively moderate , rather than extremely hot or cold , and the changes between summer and winter are also usually moderate .

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 .

Physical impacts of climate change <=SEP=> This article is about the physical impacts of climate change . For some of these physical impacts , their effect on social and economic systems are also described .   This article refers to reports produced by the IPCC . In their usage , `` climate change '' refers to a change in the state of the climate that can be identified by changes in the mean and/or variability of its properties , and that persists for extended periods , typically decades or longer ( IPCC , 2007d :30 ) . The climate change referred to may be due to natural causes and/or the result of human activity .