Climate Change - There's No Going Back

Here's some tough news for global warming deniers - the climate we once knew is gone and it's not coming back, at least not for many centuries to come.

The US government's own Climate Change Science Program has issued its report on what lies in store for agriculture, water resources and biodiversity over the next five decades and it's clear that big changes are in store.

The rise in concentrations of carbon dioxide in the atmosphere from human activities is influencing climate patterns and vegetation across the United States and will significantly disrupt water supplies, agriculture, forestry and ecosystems for decades, a new U.S. government report says. From the International Herald Tribune:

"The changes are unfolding in ways that are likely to produce an uneven national map of harms and benefits, according to the report, released Tuesday and posted online at climatescience.gov.

According to the report, Western states will face substantial challenges because of growing demand for water and big projected drops in supplies.

From 2040 to 2060, anticipated water flows from rainfall in much of the U.S. West are likely to approach a 20 percent decrease from the average from 1901 to 1970, and are likely to be much lower in places like the fast-growing Southwest. In contrast, runoff in much of the Midwest and East is expected to increase that much or more.

Farmers, foresters and ranchers nationwide will face a complicated blend of changes, driven not only by shifting weather patterns but also by the spread of non-native plant and insect pests."

From the CCSP summary:

Grain and oilseed crops will mature more rapidly, but increasing temperatures will increase the risk of crop failures, particularly if precipitation decreases or becomes more variable.

Higher temperatures will negatively affect livestock. Warmer winters will reduce mortality but this will be more than offset by greater mortality in hotter summers. Hotter temperatures will also result in reduced productivity of livestock and dairy animals.

Forests in the interior West, the Southwest, and Alaska are already being affected by climate change with increases in the size and frequency of forest fires, insect outbreaks and tree mortality. These changes are expected to continue.
Much of the United States has experienced higher precipitation and streamflow, with decreased drought severity and duration, over the 20th century. The West and Southwest, however, are notable exceptions, and increased drought conditions have occurred in these regions.

Weeds grow more rapidly under elevated atmospheric CO2. Under projections reported in the assessment, weeds migrate northward and are less sensitive to herbicide applications.
There is a trend toward reduced mountain snowpack and earlier spring snowmelt runoff in the Western United States.

Horticultural crops (such as tomato, onion, and fruit) are more sensitive to climate change than grains and oilseed crops.

Young forests on fertile soils will achieve higher productivity from elevated atmospheric CO2 concentrations. Nitrogen deposition and warmer temperatures will increase productivity in other types of forests where water is available.

Invasion by exotic grass species into arid lands will result from climate change, causing an increased fire frequency. Rivers and riparian systems in arid lands will be negatively impacted.
A continuation of the trend toward increased water use efficiency could help mitigate the impacts of climate change on water resources.

The growing season has increased by 10 to 14 days over the last 19 years across the temperate latitudes. Species' distributions have also shifted.

The rapid rates of warming in the Arctic observed in recent decades, and projected for at least the next century, are dramatically reducing the snow and ice covers that provide denning and foraging habitat for polar bears."

http://www.climatescience.gov/Library/sap/sap4-3/default.php

These are changes that will occur regardless of any measures that may be taken in the near future to curb greenhouse gas emissions. The forecasts are based on what exists today. Can the forecasts be worsened by failure to dramatically cut GHG emissions? Absolutely. The future could be much, much worse unless we somehow find the social and political will to make the drastic changes necessary to break our carbon addiction.

What does the future hold? I just don't see the big emitters of the world reaching any meaningful consensus in time to avoid the problems that are looming. We're struggling just to reach agreement on greenhouse gases alone and haven't even begun to come to grips with the other environmental, resource and population challenges that, taken collectively, could pose as great a threat to mankind as global warming itself.

One thing is clear. In terms of climate change, there's no going back. In addition to wrestling with GHG emissions we also need to be taking action, now, on remediation and adaptation. Of course that too is hampered by the heel-draggers fighting the rearguard action on emissions controls. The last thing they want is an informed, public discussion of just what does lie in store for our countries in the next half century.