Saturday, March 14, 2015

Climate Change Part 16: Future (and present) Impacts

Note: This program first aired on February 2, 2014.

Over the past weeks and months our climate change series has told us quite a tale about Earth’s climate system and how it is changing. We’ve looked at how the green house effect works and what gasses enhance it, what the parts of the climate system are and how they interact in very basic terms, and where the carbon comes from and where it goes. We’ve laid the ground work and now we’re coming to the final chapter of this story, the one in which we find out what happens next. 

And what happens next is a story of degrees. If you have a chance, read through the Intergovernmental Panel on Climate Change’s 2014 Summary for Policy Makers-it’s available freely online. In it scientists clearly lay out the risks of various impacts on natural ecosystems and human societies. The devil is in the details, if global average temperatures increase only 1 to 2 degrees Celsius, the impacts are “considerable”. If temperatures increase 4 degrees or more, the risk become high or very high. The different in temperature increases reflect different emissions scenarios. Two things remain important to understand, first that under all assessed future scenarios some risk of adverse impact remains, and second, risks are substantially reduced under low emissions scenarios. Simply put, no matter what, change is coming, but we still have some say in just how much change it is.

And what can we anticipate in the coming century (and indeed it is a hundred year horizon that these predictions mainly look towards)? Where to start? Risks from climate change are extensions of much of what we see taking place already. As temperatures increase, so do the risks, significantly.  If we look at the pure ecosystem impacts, we can anticipate a continued decline in biodiversity and an increased in extinctions for organisms that can’t adapt and or migrate to follow shifting favorable climate regions fast enough. Weakened ecosystems then become vulnerable to additional problems like diseases vectors and invasive species. These kinds of impacts are what many of us think of when we worry about climate change, as well we should, but we also need to remember that intact ecosystems provide vital services like cleaning water and air, and thus, negative impacts to natural ecosystems also have a negative impact on us. All of the other risks the IPCC report outlines are ones that directly impact the functioning of human society. Fresh water resources are projected to decline due to increased drought, especially in already semi arid areas. At the same time increased precipitation events are expected, which sounds like a good thing, except for when the additional inches of rain all fall at once. Then we have catastrophic flooding, and waste water systems that get overwhelmed, leading to increased pollution of surface water. High latitude areas may see increased freshwater resources, which brings up an important point—there can be effects that have a positive impact. Though, so far the projected negatives have outweighed the projected positives in virtually all areas of assessment.
Food security is another area where climate change is expected to negatively impact the human condition. Wheat, corn, rice and soy are the 4 most widely grown crops world wide, and increasing temperatures are projected in negatively impact the production of three of them (all but possibly soy). Decreased crop yields due to heat and water stress are likely to be the biggest issue, but problems arise with access and distribution as critical infrastructure is weakened by severe weather events. As annual crops, intensive breeding may be able to effect adaptation in a relatively short period of time, and had already yielded some more heat ready, drought tolerant varieties. The question remains, just how hot will it get? How much heat tolerance do we need to breed into these staple crops? These are just a couple of examples of what is coming between now and the end of the 21rst century. We’ll look at others in the coming weeks.

What we find as we dive increasingly deeper into the thought exercise that is “preparing for climate change”, is that while science has identified many negative ecosystem impacts, the things human society needs to pay attention to are the things that enable our “normal” day to day lives, the things that are easy to take for granted. Climate change seems very far away when you hear about a frog in the central American rain forest that has gone extinct, it’s much closer to home when you go to the sink for a glass of water and nothing comes out of the tap, just ask the folks in California. We’ve looked at the science, in this final chapter we’ll be looking at the human part of this story. 

The Summary for Policy Makers (Summary being code for a document that is still 34 pages long) of the 5th IPCC report on climate change (2014):

This document is highly recommended, if still a bit dense. It contains many excellent graphics that accompany the assessment of risk.

Portland Press Herald (from the Washington Post) on the new NOAA NASA study:

U S Navy predicts an ice free Arctic in ths summer by next year +/-3 years…