There have always been extreme weather events, so why are scientists talking so much about extreme events now?

Recent climate research synthesized in the 2007 and 2014 Intergovernmental Panel on Climate Change Assessment Reports documents that there have been observable changes in extreme weather events over the past fifty years that are consistent with the expected impacts in a warming climate. The report shows that there has been a significant shift towards fewer cold and more heat extremes across many parts of the globe over the past fifty years. The 2014 National Climate Assessment reaffirms that U.S. average

How do trees and other vegetation affect urban mesoclimates and microclimates?

Vegetation affects urban mesoclimate and microclimate by intercepting solar radiation, directing air movement, and affecting air temperature.  Microclimate, mesoclimate and macroclimate can be used to describe the climate of a given location. Macroclimate covers hundreds of square miles and parameters such as precipitation levels, temperatures and winds. Mesoclimate covers areas of tens of square miles and describes how conditions vary from the prevailing macroclimate due to the effects of water bodies, topographic features (terrain), and other landscape influences. A microclimate …