Congress currently is debating climate change legislation while President Obama prepares for the December United Nations climate change conference in Copenhagen. The outcomes of these two efforts could dramatically impact the Hawaiian Islands.

Hawai'i's mild, wet climate and isolated mountainous terrain support native plants and animals found nowhere else on earth. As an island community, we are dependent on this natural richness — our forested watersheds and living reefs — for water, food and cultural sustenance. All this is at risk as global concentrations of greenhouse gases rise.

In June, the Obama administration released "Global Climate Change Impacts in the United States" authored by leading experts from government agencies, universities, and research institutions. One key finding states, "Global warming is unequivocal and primarily human-induced." The report also confirms what other scientific assessments have concluded: Pacific Islands are particularly vulnerable to climate change.

Experts agree that climate change will not affect every place the same way. Some areas of Hawai'i, for instance, will get wetter and some drier; some will flood periodically and some permanently. Yet studies reveal several disturbing trends. Air temperatures rose across the Hawaiian Islands during the past century. For the last 60 years rainfall and stream flows decreased. And our marine environment continues to acidify.

Seas are projected to rise more than three feet by 2100 and already have risen enough to impact Hawai'i's coasts, making vulnerable our shoreline communities, wetlands, and makai industrial infrastructure. Harbor and coastline changes could disrupt shipping and refining, leading to product and food shortages. Sea-level rise has implications for Hawai'i's ability to support climate refugees from our Pacific neighbors. The Marshall Islands, Kiribati and Tuvalu may be uninhabitable by the end of this century.

Rainforests will shrink as warming continues, reducing watershed areas critical to recharging freshwater aquifers. The mauka birds, plants and other native species dependent on Hawai'i's mountain rainforests are at risk because temperatures rise faster at higher altitudes. Studies show that as temperatures rise, native birds at higher elevations are more vulnerable to diseases, face more competition from non-native birds and suffer from reduced food sources as native plants change their flowering cycles or die out completely.

In Hawai'i, environmental health means economic health. During the past 14 years, warming ocean temperatures, coupled with acidification, have already affected coral reefs, which are vital for sustaining fisheries and tourism, have intrinsic biodiversity and cultural values, and protect coastlines against wave erosion. In 2004, economists estimated the net annual benefits of Hawai'i's reefs to be $360 million, with a conservative overall asset value of nearly $10 billion. We all share an interest in keeping people, economies, and nature healthy and secure.

There are steps we can take to reduce local impacts from climate change, including:

• Minimize stressors such as invasive species and polluted runoff.

• Reduce our individual and collective greenhouse gas emissions.

• Engage in reforestation for sequestration and other benefits such as watershed enhancement, erosion control, native species protection, and sustainable wood/forest products.

• Plan for a strategic retreat of development and infrastructure away from vulnerable coastline areas,

• Change the setback to widen the buffer zone along beaches.

• Plan for key land purchases or incentives for preservation of coastlines, wetlands, streams, and forests as part of an overall strategy of adaptation to climate change.

It is also imperative that Hawai'i create a comprehensive Climate Change Adaptation Plan, so that today's short-term decisions do not make future actions more difficult. In creating this plan, the state should partner with all stakeholders, including representatives of Hawaiian cultural, business, nonprofit and religious organizations.

The first step is to assess current and future impacts on native species, ecosystem services, cultural resources, coastlines, transportation systems, utilities, food production, public health, and land use. The plan should also acknowledge changes already taking place — rising sea level, warmer temperatures, reduced freshwater availability and ocean acidification.

It will take all of us working together to keep our islands resilient to climate change. Now is the time to demonstrate decisive leadership so that Hawai'i will continue to support a thriving natural and cultural heritage while adapting to global change.