Caring for Our Forests in the Face of Climate Change
How forests, wildlife, and water in Hawaiʻi are impacted, and what the Division of Forestry & Wildlife is doing to prepare & respond
Hawaiʻi's extinction crisis meets the global climate crisis
From mauka to makai, Hawaiʻi's natural resources hold ecological and cultural significance and must be diligently protected. Hawaiʻi is home to over 25,000 species, many of which are found nowhere else. Due to a variety of threats (such as habitat loss, invasive species, and disease) those species are at risk: Hawaiʻi has more threatened and endangered species than any other state. Many species have already gone extinct. Now, our already-imperiled species face an additional set of challenges: changing climates have the potential to broadly impact many aspects of life in Hawaiʻi, including our environment, economy, and communities.
This StoryMap specifically looks at seven different types of climate change impacts related to the forests, wildlife, and freshwater resources managed by the DLNR Division of Forestry and Wildlife (DOFAW), and how we are working to address those impacts. Though there are likely to be many ways in which climate change impacts the environment around us, these eight examples cover some of the most pressing issues we face as natural resource managers. Scroll down through our list, or use the menu above to jump to a topic that interests you.
1: Changing rainfall patterns may mean more drought in some areas, flooding in others, and instability in our source of fresh water.
The problem
Since 1920, rainfall has decreased across Hawaiʻi, with the strongest drying trends occurring over the last 30 years. [1] Severe droughts have become more common and occur in both the wet and dry seasons, affecting all five major islands. [2] On Mauna Kea, drought conditions were observed in 74% of months between 2000 and 2011. [3] Declining rainfall and the resulting drought enhance wildfire risk, devastate threatened and endangered species, and reduce freshwater resources. [4]
Photo: A dry area on Molokaʻi
What we're doing about it
Rainfall in our watershed forests is our only source of fresh water in Hawaiʻi. With over half the original forest gone [6] , our forests and freshwater source are under threat. Invaded forests aren't as effective at collecting water: strawberry guava forests transpire 27%-53% more water than native forests [7] . DOFAW's Watershed Initiative aims to protect 30% of high priority watersheds by 2030, in part to protect our source of fresh water and increase our water security. A part of the Watershed Initiative includes managing programs like the Watershed Partnerships Program.
Photo: Kauai Watershed Alliance ungulate (hoofed animals) fencing
Watershed Partnerships are alliances of public and private landowners who work collaboratively to protect watershed forests for water recharge, conservation, and other ecosystem services. Today there are ten statewide Watershed Partnerships on five major islands [8] . Management actions include fencing to keep hoofed animals (goats, deer, cows, and pigs) out of high-value watershed forests, invasive species control, and outplanting. By protecting our watershed forests, we protect against drought, flooding, erosion, and loss of drinking water.
Photo: Koʻolau Mountains Watershed Partnership weed control on Oʻahu
2: Changing climates lead to more extreme weather events.
The problem
Climate change is causing more extreme weather events. Sea surface temperature increases create more frequent and more intense El Niño years, which in turn causes irregular, extreme weather like drought, heavy rain, and intense tropical storms. [9] Hurricane Iselle in 2014 is a recent example of an extreme weather event: it caused upwards of $50 million in damage. The majority of this damage was caused by fallen non-native trees, namely the invasive species albizia. [10]
Photo: New York Times image - Damage from Hurricane Iselle (2014)
What we're doing about it
DOFAW administers the interagency Hawaiʻi Invasive Species Council (HISC) , which developed the Strategic Plan for the Control and Management of Albizia in Hawaiʻi to find ways to reduce weather-related damage from this highly invasive tree. Because extreme weather can lead to flooding and erosion, DOFAW can help address this climate impact by protecting native forests that intercept rain, slow runoff, and anchor forest sediment. [11] DOFAW is also restoring wetlands like Kawainui Marsh , which can help slow floodwater velocity and reduce sediment, which decreases erosion. [12]
Photo: Kawainui Marsh State Wildlife Sanctuary on Oʻahu
3: Warmer, drier climates mean larger, more frequent wildfires.
The problem
Over 98% of fires in Hawaʻi are human-caused. [13] Warmer temperatures, periods of drought, and fire-prone invasive grasses have increased the frequency and potency of wildfires in Hawaiʻi. The average area burned per year in Hawaiʻi has increased 400% over the past century. [14] According to the Pacific Fire Exchange , the percentage of land area burned per year in Hawaiʻi exceeds the national average, sometimes surpassing the western states. [15]
Photo: A 2018 fire on Oʻahu
Wildfires pose multiple threats to natural and cultural resources. In addition to direct loss of resources during a fire, the loss of vegetation after wildfires increases rates of erosion, landslide danger, and the amount of sediment deposited into streams and nearshore coral reef ecosystems. [16] When a native forest burns, the burned area may be taken over by invasive plants. [17]
Photo: 2021 scorched Koa and Uluhe
What we're doing about it
DOFAW is responsible for fire response on nearly 60% of the land statewide. DOFAW supports several different agencies with programs to prevent and suppress wildfires in Hawaiʻi. One of DOFAW's biggest partners is the Hawaii Wildlife Management Organization (HWMO) , with whom DOFAW partners on Firewise USA : a program to help communities minimize fire risk through guidance on landscaping, vegetation maintenance, and development of emergency action plans.
Photo: 2018 fire response on Oʻahu
Photo: the stark difference fuelbreaks can make at Kaheawa wind farm on Maui
4: When habitats are altered by climate change, invasive species move in.
The problem
Hawaiʻi's native species evolved in a pre-human era where temperatures were generally lower. Those native species may be at a disadvantage as climates change and become less similar to the climates in which our native species evolved. As humans continue to bring invasive species from other parts of the world to Hawaiʻi, those new species may be well-equipped to take advantage of warmer, drier climatic conditions.
Photo: Miconia, a highly invasive plant, nicknamed the "green cancer of the Pacific"
Invasive plants and animals can also make the impacts of climate change worse. When invasive plants like strawberry guava invade and replace native forests, aboveground biomass can drop [18] , and less water can end up entering our soil and becoming part of the freshwater system that we rely on.
Photo: DOFAW staff removing strawberry guava infested forest
What we're doing about it
DOFAW staff control invasive plants and animals on state lands where possible, and restore native species as one tool to create more resilient ecosystems in the face of changing climates. In addition to the Watershed Partnerships , DOFAW partners with the Invasive Species Committees statewide to address top threats on each island. The Hawaiʻi Invasive Species Council (administered by DOFAW) recently became part of the Pacific RISCC (Regional Invasive Species and Climate Change Management Network), which is part of a national collective of climate scientists and invasive species managers working to better understand the connection between invasive species and climate change.
Photo: Staff with the Oʻahu Invasive Species Committee removing miconia by hand
5: Warmer climates allow invasive mosquitoes to carry deadly diseases to our mauka forest birds.
The problem
Hawaiian forest birds are at risk of extinction due to invasive mosquitoes, which carry deadly diseases like avian malaria. Climate change makes this problem worse, as high-elevation forests that used to be too cold for mosquitoes are now warming and seeing mosquitoes move into the last remaining habitats for native forest birds. [19] A single bite from a mosquito carrying avian malaria can infect an ‘iʻiwi or kiwikiu, potentially leading to death. [20] These native forest birds, which are found nowhere but Hawaiʻi, have unique songs. If we lose them to the effects of climate change, we also lose the music of our forests.
Photo: Diagram depicting how avian malaria is impacted by warming climate
What we're doing about it
DLNR is a member of Birds Not Mosquitoes, a partnership working to save Hawaiian forest birds by reducing the presence of invasive mosquitoes. The primary tool proposed to reduce the number of mosquitoes in our forests is a bacteria that acts as a mosquito birth control, which prevents females' eggs from hatching. This tool has already been used around the world to reduce the risk of mosquito-borne disease to humans, but the Birds Not Mosquito project would be the first time it would be used to help save birds. You can learn more at the Birds Not Mosquitoes website.
Image: The most endangered Hawaiian honeycreepers
Photo: 'Palila, one of the most endangered Hawaiian honeycreepers
7: Warmer, drier habitats may lead to more plant extinctions.
The problem
Climate change threatens Hawaiʻi's native plants. Dr. Maggie Sporck-Koehler, a former DOFAW botanist, said, “As Hawai‘i is anticipated to become increasingly warmer and drier, the best habitats for rare plants are likely to contract, extend to higher elevations, or disappear altogether.” [21] Today Hawaiʻi is often referred to as the “Endangered Species Capital of the World” with more than 100 plant taxa extinct, over 250 considered to have 50 or fewer individuals remaining in the wild, and 423 Hawaiian plant taxa threatened or endangered. [22]
Photo: 'Akoko (Euphorbia haeleeleana), the Kauaʻi spurge, is an endangered species of flowering tree endemic to the islands of Kauaʻi and Oʻahu.
What we're doing about it
DOFAW's Rare Plant Program works alongside the Plant Extinction Prevention Program to prevent plant extinctions by finding rare plants, helping with their pollination (including pollinating them by hand!), collecting seeds to grow in nurseries, and outplanting rare plants back into the forest. They also construct fences to protect rare plant habitats from hoofed animals. DOFAW has also produced codes of conduct for hikers and photographers to make sure their actions don't harm rare plants. The codes are available on our website.
Photo: DOFAW staff constructing fencing in west Maui
Photo: Fenced Cyanea horrida, a native plant endemic to east Maui
8: Damaged forests store less carbon.
The problem
Healthy forests can help sequester (store) carbon, and can help offset carbon emissions by utilizing carbon dioxide. Conversely, reducing the health of our forests can decrease our ability to store carbon.
Pigs also threaten the health of our mauka forests by uprooting soil, which causes substantial carbon emissions and exacerbates climate change.
Photo: Highly degraded leeward slopes of Haleakala on Maui
What we're doing about it
In addition to protecting our remaining native forests, DOFAW works to restore damaged areas as a tool to fight climate change. The division has multiple carbon initiatives related to forests. One example is the Pu‘u Mali Forest Carbon Project in the Puʻu Mali Restoration Area (PMRA). This area includes 5,500 acres that used to be prime forest habitat before being converted into agricultural land. Since 2004 DOFAW has conducted a forest restoration program in the area, which will also provide a long-term habitat for ʻPalila (a critically endangered finch-billed species of Hawaiian honeycreeper). Reforestation will withdraw an estimated 98,000 metric tons of carbon from the atmosphere.
Photo: Outplanting in Puʻu Mali Restoration Area
Protecting landscapes from hooved animal allows Hawaii’s native plants to naturally regrow when there is a seedbank. This area on the south slope of Molokai was mostly barren due to hoofed animals. Now, decades after a fence was constructed and hoofed animals removed, the forest is naturally regrowing.
Additional Resources
There are many other climate impacts in Hawaiʻi that are outside of the scope of work by DOFAW. In particular, sea-level rise as a result of climate change is a major issue that is being addressed by many agencies and partners. You can watch the DLNR video Rising Seas in Hawaiʻi to learn about sea-level rise impacts and the Lehua Island Ecosystem Restoration Project to learn more about higher elevation habitats. To find additional resources about climate change in Hawaiʻi, visit the Hawaiʻi Climate Portal.
Climate change background information
We use the term "climate change" to mean "changes in the Earth's climate-driven primarily by the burning of fossil fuels and deforestation, causing a relatively rapid increase in carbon dioxide concentration in Earth's atmosphere.” [23]
According to NOAA, global surface air temperatures have increased at an average rate of 0.13°F per decade since 1990, with more rapid warming at 0.3°F per decade since 1970. In the Hawaiian islands, air temperatures have increased by 0.07°F per decade between 1919-2006, with faster increases of 0.36°F per decade since 1975. NOAA projection for the future include increases of 3.6°F to 6.3°F in average annual temperature by 2100, with more increases at higher elevations, and more frequent and intense extreme heat days. [24]
While an increase of a few degrees may not seem like much, it can lead to big impacts. The increase in average temperature since 1880 has been about 1.4°F, and this has already led to more intense rainstorms, severe droughts, heat waves, rising seas, and species extinction. [25] What impacts will we see in the future, based on projections of a 3.6°F to 6.3°F increase?
According to the United Nations (UN), the effects of climate change around the world include hotter temperatures, more severe storms, increased drought, a warming/rising ocean, loss of species, loss of food, an increase in health risks, and increases in poverty and displacement. The effects of climate change will be felt first and most significantly by small island states like Hawaiʻi, where sea level rise, coastal erosion, and coral bleaching will be more noticeable than in land-locked areas.
This graph from climate.nasa.gov shows the amount of carbon dioxide in the atmosphere over the last 800,000 years. Carbon dioxide (or CO2) is a "greenhouse gas," meaning that it traps heat and that the more we find in our atmosphere, the warmer our atmosphere is likely to be. The older measurements are from air trapped in ice cores. New carbon dioxide data is recorded, in part, in Hawaiʻi at the Mauna Loa Observatory of the National Oceanic and Atmospheric Administration (NOAA). The graph shows that while levels of carbon dioxide have gone up and down over time, there is a large, sudden increase following the start of the industrial era (around the year 1850).
As the amount of carbon dioxide in the atmosphere increases, temperatures increase. This graph from NOAA shows average temperatures in Hawaiʻi since 1950. While temperatures go up and down over the course of a year, the overall trend over several decades is a higher average temperature. Though this data is for Hawaiʻi, average temperatures are increasing around the world.
The following graphs show data related to climate change and its impacts on rainfall and drought in Hawaiʻi.