Humans Cause Climate Changes

Humans Contribute to Extreme Weather – and Suffer its Consequences

Rigorous analyses have shown that natural variability alone cannot explain the observed long-term trends of changing extremes in temperature and precipitation.¹²
In contrast, the observed trends fit well with our understanding of how climate change drives changes in weather. Computer models of the climate that include both natural forces as well as human influences are consistent with observed global trends in heat waves, warm days and nights, and frost days over the last four decades.¹³ Human influence has also been shown to have contributed to the increase of heavy precipitation over the Northern Hemisphere.¹⁴
Extreme weather events do not have a single cause but instead have various possible contributing factors – and human-induced climate change is now one of those factors.
Weather variability can be extremely costly. One estimate finds that the total U.S. economic output varies by up to $485 billion/year owing to weather variability.¹⁵ From 1980 to 2010 there were 99 weather disasters in the U.S. in which damages exceeded $1 billion. Altogether those disasters cost $725 billion.¹⁶ In 2011, the costs of all weather-disaster damages so far has climbed past $35 billion, according to NOAA estimates. As of August 30th, the U.S. has witnessed 10 weather disasters costing over $1 billion each. This breaks the previous record for the number of such U.S. weather disasters in an entire year.¹⁷
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.¹⁸ 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. Death, disease, displacement, and economic hardship may follow, as we have seen with recent hurricanes, floods, heat waves, and droughts.https://www.blogger.com/blogger.g?blogID=6565483752503740244#editor/target=post;postID=2540031911680861164