Powering our future with weather, climate and water A large part of my presentation will address Extreme events A few words on the meeting organized yesterday (FIM) Global warming : an overview (IPCC AR4).

Weather forecasts and hydrological information are a part of daily life in industrial countries but are largely absent from developing countries Development, climate and hydro-met services Health and disaster risk reduction Industry and Energy Agriculture and Water How to develop sustainable hydro-met services ?

1) Human activities are modifying the composition of the atmosphere in greenhouse gases (important and rapid) IPCC 2007 : we are certain of 2) Warming is uniquevocal Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations. Numerous uncertainties remain Carbon dioxide + 39 % Methane +150 % Nitrous oxide + 20% 3) Warming will continue 2010

Temperature difference between 2010 /1970 (Hansen et al., 2011) Average global warming de 0.66 ° ; more than twice in the Arctic

A1B is a typical « business asusual scenario » At the end of the century (2090 – 2099), the projected global warming is of 2.8°C (average value) Much of land areas warms by ~ 3°5 C ; Arctic warms about 7°C ; less if less emissions ; more if more emissions

Our activities have little influence on the climate of the coming decade B1 983 GtC A1B 1499 GtC A GtC 2.8°C But the climate at the end of this century depends on our activities 1.8°C °C

Numerous impacts : more frequent heatwaves increased risk of droughts in some regions increase risk of floods in other regions more intense precipitaion events risk of more intense cyclones sea-level rise, permafrost melting ocean acidification, ecosystems, health agriculture, tourism, infrastructures… Précipitations WinterSummer Temperatures Numerous uncertainties : emission scenarios importance of global warming regional characteristics, précipitation clouds, aerosols evolution of ice sheets climatic surprises ……..

WinterSummer Africa is particularly vulnerable

More droughts in some regions

Between 20 and 60 cm unti 2100, may be more Risk of a few meters in a few centuries Deltas World population should rapidly increase in coastal areas with increasing risks linked with sea-level rise

Natural causes (solar activity, volcanoes) Observations Anthropogenic activities Greenhouse gases and aérosols natural causes Most of the observed increase in global average temperature since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentration Have human activities already affected our climate?

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