The uncontrolled global experiment of manmade warming is working visible change on earthly life at all scales, from genes to species relationships, and at a rate that may require genetic engineering to head off catastrophe.
That’s the conclusion of a new paper in the prestigious journal Science, wherein a multidisciplinary team of 17 scientists surveys the state of biological knowledge about climate impacts on organisms from water fleas to polar bears — including food sources from wheat to salmon.
“Previous reviews have covered many of the obvious changes in species ranges, phenologies, and population dynamics but have usually focused on one ecological system at a time,” they write. “Here, we discuss the full range and scale of climate change effects on biota, including some of the less obvious disruptions observed in natural systems.”
Cited research runs to 191 footnotes in this paper; the authors express regret that they couldn’t list all the work they looked at because of Science’s length limits.
So you could say they were thorough, and for coherence they organized their assessment into 94 core ecological processes that “underpin ecosystem functioning and support services to people,” such as population health, inhabited range, migration patterns, maintenance of body mass.
Of these 94 core processes, 82 already show evidence of climate impacts: population declines (and occasional increases), shifts in natural range and migration patterns, altered gender ratios, shrinking body mass due to the “increased metabolic costs of living in a warmer world.” In the aggregate the news is not so good:
The many observed impacts of climate change at different levels of biological organization point toward an increasingly unpredictable future for humans. Reduced genetic diversity in crops, inconsistent crop yields, decreased productivity in fisheries from reduced body size, and decreased fruit yields from fewer winter chill events threaten food security. Changes in the distribution of disease vectors alongside the emergence of novel pathogens and pests are a direct threat to human health as well as to crops, timber, and livestock resources.
Humanity depends on intact, functioning ecosystems for a range of goods and services. Enhanced understanding of the observed impacts of climate change on core ecological processes is an essential first step to adapting to them and mitigating their influence on biodiversity and ecosystem service provision.
There was a hopeful period, lasting perhaps into the late 1990s, when it was possible to think of climate change as a long-term, gradual process of adjustments that, depending on your point of view, might not be all bad.
If a warming Minnesota had weather a bit more like Iowa’s, and Manitoba became more like Minnesota’s, would that be so awful? Gotta like those longer growing seasons, especially if you’re raising corn or beans or wheat for the world market.
This was a blend of wishful reasoning and folk wisdom, founded on an expectation that plants and animals — perpetually evolving anyway, right? — and their relationships could not only keep pace with the changes in temperature, precipitation and other factors but would do so in an integrated, virtually coordinated way.
Too many people, including some scientists, still hold onto that wistful thinking. But as global warming accelerates, and a host of climate-change indicators also pick up the pace, a much bleaker picture seems more likely: that climate change will drive the disaggregation of natural systems, because their members will adapt at vastly different velocities.
Phytoplankton in Venezuela’s Gulf of Cariaco, the new paper notes, have adapted to a 15-year change in water temperature of about three-quarters of 1 degree Celsius “by adjusting their thermal niche” by a half-degree. A certain Daphnia water flea has adapted to warming conditions in the UK, as has a cornflower in France, and it seems likely that some corals will be able to respond in a similar way (very good news considering the grim state of the world’s great reefs).
But there is “little documented evidence of evolutionary change from species of longer generation time such as birds, mammals, and trees.”
Shifts in species’ ranges are creating new “hybridization zones” worldwide, in which closely related creatures change their gene pools through interbreeding in newly shared territory. In North America, black-capped and Carolina chickadees are an example; so are the northern and southern flying squirrels; so are native cutthroat and invasive rainbow trout.
On whether these outcomes are “good” or “bad,” the authors decline to opine.
We do not differentiate between “positive” (adaptive, buffering, or mitigating) and “negative” (stress or damage) responses because responses may be positive at one end of biological organization (such as genetic adaptation to climate change) but negative at another (such as reduced genetic variation in capacity to deal with other stressors).
Upsetting the balances
But as readers we are entitled to draw our own conclusions about the paper’s many examples of disaggregation already in evidence as species move to warmer or cooler latitudes, altitudes or watery depths, often without essential prey resources or predator controls:
- All across North America, many types of coniferous trees are beset by beetles and other insect pests whose populations are exploding, while those of their predators are not.
- In western Australia, seaweed beds killed off by rising temperatures had begun to recover, but are now being overgrazed by fish that are expanding their range to include this territory.
- Although plant growth generally is on the rise around the world because of more plentiful carbon dioxide, there are places where the weather is simply too hot or water too scarce. Across the Congo and much of the Amazon region, for two pertinent examples, productivity of forest biomass is down.
- A range of human diseases transmitted by mosquitoes and ticks is on the rise — from chikungunya to dengue to Zika to Lyme — as is the bacterial pathogen that causes Vibrio infections.
Given considerable gaps in the data about species responses to climate, the authors concede there is every likelihood that their findings understate the extent of these impacts, and therefore can be taken as a conservative assessment. Conservative, perhaps, but still grim, as in this passage devoted to important food species:
Long-term trend analyses show convincingly that a commercial fish species in the North Sea underwent simultaneous reductions in body size over a 40-year period because of ocean warming, resulting in 23% lower yields. Reduced body size in fish is also being recorded in lakes and rivers throughout Europe and has been linked to increased temperature and climate-induced shifts in nutrient inputs….
Yields in rice, maize, and coffee have declined in response to the combined effects of rising temperatures and increasing precipitation variability over past decades… [There have been] high levels of genetic changes in the progenitors of cultivated wheat and barley in Israel over the past 20 years. These wild cereals exhibited landscape-level changes in flowering time and a loss of genetic diversity in response to increasing temperatures.
The solution to problems in the grain supply, they feel, is genetic engineering of crops to instill resistance to climate change. And, in fact, “human-assisted evolution” is about the only strategy they offer for responding to other changes already under way and more or less across the board, whether the focus is grain crops, timber or the world’s failing fisheries.
“Time is running out for globally synchronized response to climate change that integrates adequate protection of biodiversity and ecosystem services,” they observe.
I might add that situation is all the more fraught if the only feasible way to redress the damage of one uncontrolled global experiment is to pick up the pace on another.
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The full paper, “The broad footprint of climate change from genes to biomes to people,” can be found here but access isn’t free. I wish I could point to other good press treatment of the work, but coverage has been quite light; I think I first saw it mentioned in the UK Independent, whose decent report is here.