As a professional conservationist, I’m haunted by the thought of a future retrospective on the most pressing environmental issue of our time: climate change. We’ve been warned for two decades that if we don’t act soon, and act decisively, the world will be a much harsher and less inhabitable place. Yet we’ve been unable to change course in any significant way. Those who inherit this world will want to know—what were they thinking?

In his 2005 book "Collapse: How Societies Choose To Fail or Succeed," Pulitzer Prize-winning scientist Jared Diamond tells the story of Rapa Nui (Easter Island), where a vibrant culture became a lost civilization after destroying its natural environment.

"I have often asked myself," writes Diamond, "what did the Easter Islander who cut down the last palm tree say while he was doing it? ‘Jobs not trees? Technology will save us? We don’t have proof, we need more research?’"

The warming of Earth’s climate is not in doubt; 98 percent of the world’s climate scientists believe the phenomenon is real and man-made — produced by human activities such as deforestation and the burning of fossil fuels. These findings are recognized by the national science academies of all major industrialized nations and by the International Panel on Climate Change, a scientific body with 194 member countries.

The problem is not only real, it’s urgent. Over the past century, Earth’s average surface temperature has increased by about 0.8 °C (1.4 °F), with about two-thirds of the increase occurring since 1980.

Scientists say that to avoid catastrophic change, we must keep the increase to no more than 2°C, or 3.5°F. Yet at current world emission rates, we are on a trajectory to increase temperatures by twice that amount before the end of the century.

For a half million years prior to the Industrial Revolution, atmospheric carbon dioxide (CO2) stood at about 280 parts per million. It is now 390 ppm and rising. According to NASA climate research scientist Dr. James Hansen, if humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, CO2 levels will need to be reduced to at most 350 ppm. "If the present overshoot of this target CO2 is not brief, there is a possibility of seeding irreversible catastrophic effects," he warns.

We are already seeing broad evidence of a changing climate — more intense hurricanes, ice storms and heat waves on the mainland U.S.; droughts in Texas and Africa; catastrophic floods in Pakistan and Australia; coral bleaching and melting polar ice caps.

Since 2000, we’ve seen 10 of the 11 hottest years on record. Just last month, the U.S. had the warmest March since record keeping began in 1895. The average temperature was 8.6° above the 20th century average, with more than 15,000 U.S. warm temperature records broken.

University of Hawaii climate change law professor Maxine Burkett notes our own extreme weather, in March 2006: "a biblical rain lasting 40 days and 40 nights." Floods. Sewage overflows. Beach closures. Nine mudslides onto Round Top Drive blocked the main road to my own home for 20 months, and cost millions to repair.

Here in Hawaii, climate change is an imminent and unprecedented threat to our natural systems — our forests, coastlines, coral reefs and wetlands. Even if we drastically reduce CO2 emissions now, we will still feel the effects, including more frequent and severe storms, increased runoff and siltation, less rainfall, higher temperatures, sea level rise and high-wave events, and climatic conditions even more conducive to invasive species.

Many of these changes are already occurring.

According to Chip Fletcher of the University of Hawaii School of Ocean and Earth Science and Technology, Hawaii’s sea level is rising now, and likely to accelerate along the lines of global or Pacific-wide sea level rise, which is more than a foot by 2050 and 2.5 to 6.2 feet by 2100. Coastlines are increasingly vulnerable; our freshwater tables will shrink.

Hawaii temperatures are increasing at a rate of 0.3°F per decade. What’s more, the UH Geography Department’s updated Rainfall Atlas of Hawaii confirms a century-long trend of decreasing rainfall and stream discharge — an overall decline of 15 percent, with greater declines in the past 30 years.

One important way we can address these impacts is to improve protection of our natural systems, in particular our forests, the source of virtually all our fresh water. Healthy and diverse Hawaiian forests act like a sponge, collecting rain and moisture from passing clouds, slowly delivering fresh water into streams and aquifers, absorbing greenhouse gases, and reducing runoff and siltation into near shore waters during storm events.

The state’s "Rain Follows the Forest" plan, a forward-looking attempt to ensure that the source of our fresh water is protected into the future, deserves our support. Key funding for the plan can come from a 10-cent fee on single-use plastic and paper bags now before the state Legislature.

Locally and globally, climate change affects us indiscriminately, from the highest saint to the lowest human trafficker. Worse, it destroys the lives of the poor and the innocent. And the greatest horror is that we did it — through our consumption, our disengagement.

But it’s not too late. Through our own personal actions, each of us can do our part to minimize the impacts. So get off your duff. If you haven’t already, replace all incandescent bulbs with compact fluorescents or LEDs, and switch over to solar hot water.

Get a hybrid car, or electric, or biodiesel. Educate yourself. Try out, responsibly and sustainably, all ways to reduce fossil fuels. Offset or reduce your carbon footprint. Plant trees. Communicate. Advocate. Help change policy.

Do it for the environment and your pocketbook. Do it whether or not anybody else does it. Participate in the process to move us forward.

Let’s change our future. That’s what I’m thinking.