Full name: Nguyễn Thanh Tùng Student code:10000820 Class: K55TTKHMT OVERVIEW: IMPACTS OF WEATHER AND CLIMATE EXTREMES WITHIN CLIMATE CHANGE – PRECIPITATION AND DROUGHT     I Overview: Weather and climate extremes Increase in average temperature leads to big changes in extreme weather Impacts of Precipitation and Drought Conclusion OVERVIEW T he Earth’s climate has warmed by approximately 0.6 oC over past 100 years with two main periods of warming, between 1910 and 1945 and from 1976 onwards The rate of warming has been nearly double that of the first and, thus, greater than at any other time during 1000 years1 Changes in extreme weather and climate events have significant impacts and are among the most serious challenges to society in coping with a changing climate Many extremes and their associated impacts are now changing For example, there are more unusually hot days and nights, fewer unusually cold days and nights, and fewer frost days Heavy downpours have become more frequent and intense Droughts are becoming more severe in some regions… Recent weather events such as deadly heat waves and devastating floods have sparked popular interest in understanding the role of global warming in driving extreme weather These events are part of a new pattern of more extreme weather across the globe, shaped in part by human-induced climate change As the climate has warmed, some types of extreme weather have become more frequent and severe in recent decades, with increases in extreme heat, intense precipitation, and drought In the future, with continued global warming, the phenomena of extreme weather and climate events are very likely to further increase in frequency and intensity 1|Page II INCREASE IN AVERAGE TEMPERATURE LEADS TO BIG CHANGE IN EXTREME WEATHER All weather events are influenced by climate change because all weather now develops in different environment than before European 2003 Summer Temperatures Were Far Outside Normal Range 2003 European Heat Wave: The Hottest Summer in 140 Years (1864-2003) Each vertical line represents the average summer temperature for a single year from the average of four locations in Switzerland over the period 1864 through 2003 This illustrates how far outside the normal range the summer of 2003 was Schär et al 2004 Small changes in the averages of many key climate variables can correspond to large changes in weather Substantial changes in the frequency and intensity of extreme events can result from a relatively small shift in the average of a distribution of temperatures, precipitation, or other climate variables Climate Change Shifts the Odds for Extreme Weather Events 2|Page Weather variation on our planet can be described with a rough bell-shaped curve Therefore so-called normal weather is very common while extreme weather is rare While events close to normal occur frequently, in the broad center of the curve, there is a dramatic fall-off in the frequency of events further away from normal, in the flatter ends of the curve III IMPACTS OF PREICIPITATION AND DROUGHT Precipitation: “When it rains, it pours” Precipitation has increased in many regions of the world and decreased in others, with little or no net change in total amount of precipitation Generally, wet areas have become wetter, and in contrast, dry areas have become drier in the past 40 years Over land, the precipitation record extends through-out the 20th century, and large variations occur from year to year and on decadal time scales Nonetheless, some large-scale patterns of systematic change are evident (Trenberth et al 2007a) In general, there have been decreases in precipitation in the subtropics and tropics outside of the monsoon trough, and increases in land precipitation at higher latitudes, notably over North America, Eurasia, and Argentina The decreases are especially evident in the Mediterranean, southern Asia, and throughout Africa In the more northern regions, more precipitation falls as rain rather than snow (e.g Mote 2003, Knowles et al 2006) 3|Page Heavy precipitation: The water holding capacity of the atmosphere increases in a warmer world While an atmosphere that holds more moisture has greater potential to produce heavier precipitation, precipitation events also become less frequent and shorter, as it takes longer to recharge the atmosphere with moisture In the wettest areas of the tropical oceans, the most extreme rainfall events have increased by 60% per degree of warming The higher latitudes have become wetter in recent years, due mainly to the warmer air holding more moisture and in part to alterations in atmospheric circulation driven by climate change At the same time, the subtropics and parts of the tropics have become drier as winds carry the moisture away to the monsoon rain areas or to mid-latitude storms Heavy rainfall can lead to numerous hazards, for example: flooding, landslides including risk to human life, damage to buildings and infrastructure, and loss of crops and livestock, disrupt transport and communications… Drought: Threats to Water and Food Security National Map: Drought Vulnerability In the United States, parts of the Western U.S are already experiencing water crises because of severe dry-spells, but with climate change, the entire country will likely face some level of drought 1,100 counties - one-third of all counties in the lower 48 states - face higher risks of water shortages by mid-century as the result of climate change More than 400 of these counties will face extremely high risks of water shortages 4|Page The increase in drought is caused by many factors: shortfalls in precipitation; earlier snow melt; a shift away from light and moderate rains towards short, heavy precipitation events; and increased evaporation from soil and vegetation due to higher atmospheric temperatures, all of which have been driven at least in part by climate change Increased heating leads to greater evaporation of moisture from land, thereby increasing the intensity and duration of drought Individual droughts have been linked to climate change, such as the drought that hit central India in 2008 when the north-south pattern of precipitation was disrupted by unusual weather driven by abnormally high sea surface temperatures due in part to global warming.5 As temperatures rise and precipitation decreases, water quality can be jeopardized Shrinking amounts of water can concentrate contaminants such as heavy metals, industrial chemicals and pesticides, and sediments and salts During drought, drinking water supplies are susceptible to harmful algal blooms and other microorganisms Of course, drought means more than not having access to clean drinking water Changes in precipitation and water availability could have serious consequences for commercial agriculture – crops yield less and food security suffers Drought conditions can also help fuel out-of-control wildfires Water is life, and climate change is threatening this precious resource Nearly every U.S region is facing some increased risk of seasonal drought Climate change will significantly affect the sustainability of water supplies in the coming decades As parts of the U.S get drier, the amount of water available and its quality will likely decrease - impacting people's health and food supplies Drought of course threatens our water and food supplies and is driving up the cost of everything from corn to milk Unfortunately, drought conditions are expected to become the new normal for many parts of many countries in the world if we don’t more to address climate change IV CONCLUSION Our planet is facing many terrible phenomena that are results of climate change Human contributes to extreme weather and also tries to suffer its consequences Changes in extreme weather threaten human health as well as prosperity Many societies have taken measures to cope with historical weather extremes, but new, more intense extremes have the potential to overwhelm existing human systems and structures More frequent and more severe extreme weather events are more likely to destabilize ecosystems and cripple essential components of human livelihood, such as food production, transportation infrastructure, and water management References: 5|Page Climate Change 2001 Third Assessment Report of the Intergovernmental Panel on Climate Change IPCC (WG I & II) (Cambridge Univ Press, Cambridge, 2001) Weather and Climate Extremes in a Changing Climate (page VII) Synthesis and Assessment Product 3.3 Report by the U.S Climate Change Science Program and the Subcommittee on Global Change Research EDITED BY: Thomas R Karl, Gerald A Meehl, Christopher D Miller, Susan J Hassol, Anne M Waple, and William L Murray Changes in precipitation with climate change Kevin E Trenberth - National Center for Atmospheric Research, Box 3000, Boulder, Colorado 80307, USA Climate Change and Water Supplies in the Wes Michael Dettinger, USGS Rao, Suryachandra A., Hemantkumar S Chaudhari, Samir Pokhrel, B N Goswami, 2010: Unusual Central Indian Drought of Summer Monsoon 2008: Role of Southern Tropical Indian Ocean Warming J Climate, 23, 5163–5174 doi: 10.1175/2010JCLI3257.1 … 6|Page