As our planet warms from excess carbon in the atmosphere, some of that heat is absorbed by the ocean. Fish and invertebrates are responding to warming waters by moving to higher latitudes or deeper waters where the water is cooler, and it was expected that these shifts would eventually affect availability of some commercially harvested species.

"Eventually" may be now. Ocean warming has already affected global fisheries in the past four decades, according to a new study published in Nature. By looking at catch statistics, scientists discovered that the composition of species in fisheries around the world is already shifting and changing our menu.

Scientists compared the temperature preferences of 698 commercial fish species with the size of catches to develop an index known as the “mean temperature of the catch," and this index was used to evaluate the potential effects of climate change on fisheries. They found that water temperatures rose steadily every decade between 1970 and 2006 and that the mean temperature of the catch rose significantly in 52 large marine ecosystems, which cover the majority of the world’s coastal and shelf areas.

The Open University

Invasive species have become a problem on nearly every continent, where native species that may have had millions of years to adapt to their environment are somehow trivially displaced by a species that originated somewhere else. How is it that the invaders can be so phenomenally successful against what should be a well-entrenched competition?

A new study shows that in at least one case, some insect invaders engage in a bit of biological warfare, carrying a fungus that kills their competitors (the host can tolerate the fungus). The fungus spreads because of a nasty habit the insects have—namely that they tend to eat each others' eggs. Somewhat ironically, all of this goes on in a species that tends to have a friendly reputation: the ladybug (or ladybird, for the anglophiles among us).

The invasive species in question is an Asian ladybug, the harlequin ladybird Harmonia axyridis. Because of its fondness for agricultural pests (fondness in the same sense that I have a fondness for lobster) Harmonia has been introduced to some countries where it wasn't native. When the invaders were introduced, the native ladybug species dropped like flies (pun intended), being easily displaced by the new arrivals.

A greenhouse in winter, with the rest of the tundra frozen around it.

Josh Schimel

Although the climate changes that are being driven by human carbon emissions are likely to cause serious disruptions on their own, one of the additional worries is that the initial warming will set off events that keep changing the planet even if humanity gets its carbon emissions under control. So, for example, warming the oceans could heat up the clathrates that exist there, releasing methane that greatly enhances the greenhouse warming.

The other place that scientists have been watching nervously is the Arctic. About half the carbon stored in the Earth's soil is in the Arctic, where it's locked in place by permafrost and low metabolic activity caused by the cold. As those regions melt, the worry is that bacteria in the soil will start feeding on the carbon trapped there, releasing it into the atmosphere as CO₂ that causes further warming.

A new study that looks at 20 years of changes in Alaska, however, suggests that this won't necessarily take place. In the area being studied, the warming temperatures rearranged the ecosystem and redistributed the carbon. But, in the end, there was just as much carbon stored in the soil. What needs to be determined now is just how well this experience will translate to other areas of the Arctic.

National Park Service

Animals that turn white in winter are having a mismatch with the reduced snowpack in their environments.

Measuring the impact of climate change on animals is difficult, because (a) climate change is complex and (b) animals are complex. Climate change can alter the environment in many different ways, and each of these changes can affect the food supplies, hibernation patterns, reproductive behavior, and migratory patterns of different animal species. The changes in the animals all affect each other, too, since many of them are interrelated in food chains and webs that can be hard to disentangle.

Luckily, researchers at the University of Montana stumbled upon one simple, obvious part of an animal that they could measure in response to a simple, obvious change in climate. Snowshoe hares change color from brown to white in the winter so they can be camouflaged in the snow. So do at least nine other species of cute, cuddly mammals: Arctic foxes, collared lemmings, long-tailed weasels, stoats, mountain hares, Arctic hares, white-tailed jackrabbits, Siberian hamsters, and least weasels. (Bet you didn't know that hamsters are tough enough to handle winter in Siberia.)

One of North America's many migratory birds.

Thomas Cantwell

It's been estimated that up to one in ten species could go extinct by the end of this century as a result of climate change. Conservation professionals are working hard to understand how climate change will influence species and to develop strategies to manage the risks, but migratory species pose a particular challenge. These long-distance migrants spend parts of their annual cycle in different habitats, at different latitudes, and often cross geopolitical boundaries.

Migration is an adaptive response to geographic and seasonal variation in resources, but climate change may disrupt the longstanding, and sometimes impeccably timed, relationships between migratory species and their environment. Changes in ecological conditions may be taking place on both ends of a migratory route, making it difficult to predict how climate alterations will affect a species or affect it across its range.

Climate change vulnerability assessments are used to develop an understanding of species’ vulnerability to climate change and guide management efforts. These frameworks are becoming mainstream decision support tools for conservation in the US, but they may be doing migratory species a disservice, according to a commentary published this week in Nature Climate Change.