Major Environmental Issues and Ways To Combat Them

A long list of environmental problems can be drawn up, and most of the entries turn out to be downstream of a much shorter one. Three issues sit underneath the others: the loss of biodiversity, the changing chemistry of the oceans, and a warming atmosphere. Work on those and a good deal of the rest moves with them.

Loss of Biodiversity

An ecosystem holds together because a large number of species each do something in it, and the services people rely on — pollination, soil formation, fish stocks, clean water — are the aggregate of that work rather than any single part of it. As species are lost, those services get less reliable rather than simply smaller.

The human activities that cause loss of biodiversity are dominated by habitat destruction, with pollution, direct killing and the spread of invasive species behind it. A changing climate compounds all four, because a species already confined to a fragment of its former range has nowhere to move to.

How to Combat This

• Protect habitat that is still intact, which is cheaper and more effective than restoring habitat that is not
• Reconnect fragments, so populations are not isolated in patches too small to persist
• Control invasive species early, while control is still possible
• Replant, and keep what is replanted alive long enough to become woodland

Water Pollution and Ocean Acidification

Water pollution is the older problem and the better understood one: sewage, agricultural run-off, industrial discharge, oil and plastic. Ocean acidification is the newer and quieter one. The sea has absorbed a large share of the carbon dioxide released since industrialisation, and dissolved carbon dioxide makes seawater more acidic.

That change in chemistry matters most to anything that builds a shell or a skeleton from calcium carbonate — oysters, mussels, corals, and the plankton a great deal of the food web starts with. Shells form more slowly in more acidic water, and in the worst cases dissolve faster than they are laid down.

How to Combat This

• Treat sewage and slurry before it reaches a watercourse, rather than after
• Keep vegetation along riverbanks, which holds soil and intercepts run-off
• Reduce the plastic entering the system, since removing it afterwards barely works
• Contain spills quickly, because the first hours decide most of the damage

Global Warming and Climate Change

The warming itself is no longer in question, and it is not confined to places that were already hot. The poles are warming fastest, sea ice is retreating, sea levels are rising, and the distribution of extreme weather has shifted. Rising concentrations of carbon dioxide and other greenhouse gases are the cause, and deforestation removes part of what would otherwise absorb them again.

For birds the effect shows up as timing rather than temperature. Spring arrives earlier than it did, and a migrant that leaves on the old schedule can reach a breeding ground after the peak of the food its young need.

How to Combat This

There is no single measure, and the results are gradual. Among the ways to combat global warming:

• Replant woodland, and protect the woodland that is still standing
• Cut emissions at the source rather than offsetting them afterwards
• Reduce waste, which carries an energy cost through its whole life
• Shift generation onto sources that do not burn anything

Where this leaves the list

Pollution, deforestation, poor waste management and oil spills all appear under more than one of the three headings above, which is the useful thing about reducing the list to three. Progress on any one of them shows up in the others.