Global Climate Change


There is increasing evidence that the earth's climate is changing. Global temperatures are increasing with 1998 and 2005 being the warmest years in instrumental record (at least 150 years). Ten of the hottest years on record have occurred since 2000.  Global rainfall has increased slightly in the past 100 years, and precipitation is predicted to increase as the climate warms.  In addition, and sea levels have risen 15-20 cm over the last 100 years, and is predicted to rise another half a meter (at least) by the end of this century. It is still debatable whether these changes are natural fluctuations of the climate system, or the result of human activity on this planet.  But the climate is changing! And the eveidence points more and more to human activity being responsible at least over the last 50-60 years.

It is clear that various greenhouse gases in the atmosphere have increased dramatically over the last 150 years as a result of man's activity on this planet. It is also understood that increasing the concentration of these gases results in more heat being trapped in the earth's atmosphere (greenhouse effect) causing a warming of the planet. Theoretical climate models that try to simulate the global climate predict that if we continue pumping these greenhouse gases into the atmosphere at the same rate as today, the globe will warm 2-5 degrees by 2100.

Now 2-5 degrees may not seem that big of a deal, however, during the last Ice Age 18,000 years ago, when New York City was buried under 1 km of ice, the global temperatures were only 5-6 degrees colder than today. Therefore, warming a similar amount in the opposite direction will likely result in major changes in the global climate. Possible implications for you and me? Well, changes in temperature, precipitation and sea level can effect us in many different ways depending on where we live. The tropics will be affected differently to midlatitude regions.  Coastal regions will see different impacts compared with inland regions. Dry regions may become drier, while wet regions may be wetter.

Two possible implications of a warmer climate that interest me are the possibility of more frequent and more intense thunderstorms, possibly leading to more flash floods and severe weather. In some regions climate models predict an increased frequency of drought around the globe, with natural forest fires becoming more common, and more damaging. I am interested in such implications of future climate change (see references below). The figure below shows the changes in lightning activity in an atmosphere with twice today's concentration of CO2 (equivalent to a 4oC warming in the NASA/GISS model ). Note that although globally the model predicts an increase of 30% in the global lightning activity, most of this change occurs of the continental regions.  Note that there are some regions (blue) where the model predicts decreases in thunderstorm activity.  Although our confidence in the regional changes is very low with these coarse-resolution climate models, the global trends are fairly robust from model to model.  We have also shown that lightning and thunderstorms also prefer drier climates relative to moist climates.  While Africa has much more lightning activity than the Amazon regions, the rainfall in the Amazon is greater than over Africa.  As the climate warms and dry in some regions, it may be these regions that experience more intense thunderstorm activity, while areas that get warmer and wetter see less thunderstorm and lightning activity.  We will need to wait and see....

In addition to the lightning activity increasing in a warmer climate, the small changes in surface temperature result in large changes in the lightning activity.  Hence the global lightning activity may be used to amplify any climate change signal.  This aspect of my research is discussed on the "Atmospheric Electricity" page.

Furthermore, lightning is also a major source of nitrogen oxides (NOx) in the atmosphere.  These gases are important in determining the ozone content of the lower atmosphere.  Hence, if lightning activity changes in the future due to climate change, this may also impact the chemistry of the atmosphere (see Tropospheric Chemistry page).

One of our recent projects related to regional climate change in the Middle East is the GLOWA-Jordan River.  This project was a German-Israel-Palestine-Jordan project to study the future hydrological implications of climate change in the Jordan River watershed.  This project dealt with many different aspects of the climate system, from ecology, hydrology, zoology, agriculture, botany, climate modeling, economics to planning.

References:

    Price, C., 1993: Global surface temperatures and the atmospheric electrical circuit, Geophys. Res. Lett.,20, 1363-1366.
    Price, C
., and D. Rind, 1994: Possible implications of global climate change on global lightning distributions and frequencies , J. Geophys. Res., 99, 10823-10831.

    Price, C
., and D. Rind, 1994: The impact of a 2xCO2 climate on lightning-caused fires, J. Climate, 7, 1484-1494.
    Price, C., S. Michaelides, S. Pashiardis and P. Alpert, 1999: Long term changes in diurnal temperature range in Cyprus, Atmos. Res., 51, 85-98.
    Shindell, D.T., J.L. Grenfell, D. Rind, C. Price and V. Grewe, 2001: Chemistry-climate interactions in the GISS GCM. Part 1: Tropospheric chemistry model description an evaluation, J. Geophysic. Res., 106 (D8), 8047-75.

    Alpert, P., 
C. Price, S. Krichak, B. Ziv, H. Saaroni, I. Osetinsky, J. Barkan, P. Kishcha, 2005: Tropical tele-connections to the Mediterranean climate and weather,  Advances in Geosciences, 2, 1-4.
    Alpert, P. C. Price, S. Krichak, B. Ziv, H. Saaroni, I. Osetinsky, J. Barkan and P. Kishcha, 2006: Mediterranean climate and some tropical teleconnections, Il Nuovo Cimento, 29 (1), 1-9.  
    Price, C.
, and M. Asfur, 2006:  Long term trends in lightning activity over Africa, Earth Planets Space, 58, 1-5.
    Price
, C., 2009: Will a drier climate result in more lightning ?  Atmos. Res., 91, 479-484.   
    Price, C
., 2009:  Thunderstorms, Lightning and Climate Change,  in Lightning : Principles, Instruments and Applications, ed. H.D. Betz, U. Schumann and P. Laroche, Springer Publications, 521-536.
    Llasat, M.C., M. Llasat-Botija, M.A. Prat, F. Porcú, C. Price
, A. Mugnai, K. Lagouvardos, V. Kotroni, D. Katsanos, S. Michaelides, Y. Yair, K. Savvidou, and K. Nicolaides, 2010: 
High-impact floods and flash floods in Mediterranean countries: the FLASH preliminary database,  Adv. Geosci., 23, 47-55.
     Price, C
., Y. Yair, A. Mugnai, K. Lagouvardos, M. C. Llasat, S. Michaelides, U. Dayan, S. Dietrich, F. Di Paola, E. Galanti, L. Garrote, N. Harats, D. Katsanos, M. Kohn, V.   Kotroni, M. Llasat-Botija, B. Lynn, L. Mediero, E. Morin , K. Nicolaides, S. Rozalis, K. Savvidou, B. Ziv,  2011: Using lightning data to better understand and predict flash floods in the Mediterranean, Surveys in Geophysics, 32(6), 733-751.


Related Sites:
   International Panel on climate Change (IPCC)
   Climate Model Predictions for future