Earth Day, is one of my favorite days of the year. Established in 1970 by the leadership of peace activist John McConnell and Gaylord Nelson, a Senator from Wisconsin, Earth Day is a time for all us to renew our efforts to take care of Mother Earth and all the many species that share this planet with us. At least for those of us in the Northern Hemisphere, Earth Day is well timed, occurring at the peak of spring with the promise of rebirth and renewal as plants leaf out and flower and animals return or emerge from hibernation.

Earth Day was established in the nascent days of the environmental movement. This movement was perhaps given the greatest boost by Maine’s own Rachel Carson whose 1962 book, Silent Spring, documented the devastating effect of the use of DDT on many birds.

There is no shortage of ways we can help improve the health of the earth and all of its organisms. Some ways are recycling, planting native plants in your yard, turning down the thermostat in your house a few degrees, and paying voluntary carbon offsets for your air and car travel.

Of all the insults we humans have visited on our planet, I think the emission of greenhouse gases has caused the most terrifying effects. There is no doubt that air temperatures have consistently increased over the past 100 years with no sign of slowing. Ocean temperatures are setting new high records every day!

Some denialists argue that the earth has seen great variation in temperatures over geological history and that current climate warming poses no problems. That assertion that the earth’s temperature has varied greatly is absolutely true but the rate at which global temperatures are changing is unprecedented.

Temperature has a fundamental effect on all organisms. As temperatures rise, organisms must find more optimal temperatures by moving poleward or upward on mountains. For organisms with limited mobility, perishing is the likely outcome.

Warm tropical ocean temperatures are causing widespread coral reef mortality. We expect these corals to move poleward via dispersal of their larvae to find ocean waters below lethal temperatures.

The U.S. Forest Service has released models of the distribution of trees in the northeast in the year 2100 assuming that carbon emissions continue at the same rate. Sugar maples and balsam fir will no longer be able to live in Maine. Nesting birds that depend on balsam fir forests like Swainson’s Thrush, Winter Wren and Red-breasted Nuthatch will become much less common.

Some may say, organisms can simply move toward the poles or to higher altitude to persist. The problem is that some organisms will run out of space. Polar bears depend on pack ice to forage for seals. With global warming, polar bears cannot move northward from their arctic habitat. They are in real trouble!

The science of phenology concerns the timing of biological events. Leaf-out of red maples, first flowering of white elderberry, the first arrival of Yellow Warblers in the spring, first egg-laying of Ovenbirds, the emergence of groundhogs from their hibernation burrows, the first calling of spring peepers, and the emergence or caterpillars from hibernation  are all examples.

With global warming, we expect phenological events to occur earlier. We have abundant evidence of that happening already for many plants, insects, birds, amphibians and mammals.

An insidious effect is a phenomenon called phenological disconnect. When two or more species that depend on each other fall out of sync, disaster can occur.

The Pied Flycatcher is a common Eurasian bird that winters primarily in Africa. They feed their young seasonally abundant caterpillars that feed on oak leaves. In Europe, oak trees are leafing out about two weeks earlier and the caterpillars are right with them. However, the flycatchers are on their old schedule and are arriving after the caterpillar peak has passed, leading to starvation or slower development of their chicks.

What can we do to prevent such tragedies? Earth Day should inspire us all to do all we can every day to reduce the carbon emissions that are heating our planet.