Weatherdem's Weblog

Bridging climate science, citizens, and policy

How Climate Change is Affecting Arctic Ecology

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A study examining how climate change is affecting arctic ecological dynamics was published in last Friday’s edition of the journal Science.  When scientists and activists state that the Arctic has warmed significantly beyond what the rest of the planet has yet experienced, thanks to human-forced climate change, climate change denyers and action delayers often respond with the unintelligent, “So what?”.  Well, this study is one of the first to address the “so what” in a really systematic, meaningful way.  Empirical data is being sought and reported on.  And the prognosis isn’t good.

From the study’s abstract [emphasis mine]:

Despite the buffering effect of landscape heterogeneity, Arctic ecosystems and the trophic relationships that structure them have been severely perturbed. These rapid changes may be a bellwether of changes to come at lower latitudes and have the potential to affect ecosystem services related to natural resources, food production, climate regulation, and cultural integrity.

The important factor for most people is likely to be that “the rapid changes may be a bellwether of changes to come at lower latitudes” – places where people live and ecosystems that we interact with exist.  If what is being observed in the Arctic also happens at latitudes further south, we’re in for some major disruptions.

The changes observed in this report have largely occurred over the past 20-30 years, a very short time frame climatologically speaking.  Sea ice and land snow cover have both decreased significantly over that time-span.  As a result, plant and animal life have been forced to respond to different regimes.  Some have succeeded, others are having difficulty.  Can  these ecosystems handle being perturbed from their long-term stable patterns?  That remains to be seen.  Reindeer are benefiting so far from longer growing seasons and more plentiful food sources.  Caribou and arctic foxes are not.  Plant growth is beginning earlier than caribou are calving – which means less food is available for the calves once they are born.  Arctic foxes’ domains are being displaced by warmer-climate living red foxes.

As these changes take place, carbon-budgets are being thrown out of whack.  Exchanges of gases that are present in trace amounts but in delicate balance, are being altered faster than expected.  What used to be viewed as a fairly simplistic system, the Arctic ecosystem’s complex interconnectedness is being thrown into sharp focus.  As snow and ice melts earlier every year, for example, oceans and lakes are nutrient-loaded earlier.  This has repercussions for species that depend on patterns of nutrient availability.

These same signals are being detected all over the globe.  Ecosystems are experiencing a changing world and responding accordingly.  The problem is aspects of ecosystems remain in a stable zone for a long period of time, absorbing the extra forcing and dealing with it.  Then, suddenly, things change dramatically.  We’ve only started assessing the dramatic changes in small portions of the globe.  We’ve already missed more than we’ve caught and many more will happen.  A larger problem for ecosystems and our societies is how much can larger systems absorb before they experience their own dramatic shift?  Because once they happen on larger scales, they will prove to be very disruptive to contend with.

In Colorado, for example, warmer winters, earlier snowmelt and drier summers have combined to weaken vast swaths of pine forests.  Pine beetles were available to exploit the shifting changes in a high altitude setting, which has many analogies to the changes seen in the Arctic.  As a result, hundreds of thousands of acres of pine forest has succumbed to the beetle epidemic.  Instead of a long-term carbon sink, these forests have quickly changed into a short- and medium-term carbon source.

Societies and ecosystems have toppled in the past after undergoing severe climatic stresses.  The difference now is we have the opportunity to do something about what we know is coming.

One of the future study recommendations the authors have is the following:

Extreme events, tipping points, and resilience. Insect outbreaks, sudden and transient temperature changes, rapid retreat of sea- and lake ice, bouts of abnormally high precipitation or extended droughts, wildfires, the sudden release of water from melting glaciers, and slumping of permafrost are examples of stochastic events that may have disproportionately large effects on ecological dynamics. Such processes, and ecological responses to them, may be nonlinear and difficult to predict.  We urge research aimed specifically at understanding the role of extreme events in ecological dynamics in the Arctic, in particular with regard to the build-up of tipping points in ecological systems. An important consideration for conservation and management in the Arctic, for example, is whether alteration of species composition of plant and animal communities due to climate change will lead to alternate ecosystem states or persistent instability, or whether system states can rebound from abiotic perturbations due to species resilience.

They also call for increased baseline studies so that additional future research can be compared to studies conducted over time to determine relationships and theorize about causes and effects in this complex system.

Cross-posted at SquareState.


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