Climate Change Effects on Wildlife

Climate change affects both terrestrial and aquatic biomes causing significant effects on ecosystem functions and biodiversity. Climate change is affecting several key ecological processes and patterns that will have cascading impacts on wildlife and habitat. For example, sea-level rise, changes in the timing and duration of growing seasons, and changes in primary production are mainly driven by changes to global environmental variables (e.g., temperature and atmospheric CO₂). Climate-induced changes in the environment ultimately impact wildlife population abundance and distributions.

Related Article(s):

• Climate Change
• Downscaled High Resolution Datasets for Climate Change Projections
• Predicting Species Responses to Climate Change with Population Models
• Restoration of Ecological Function in Terrestrial Systems Impacted by Invasive Species

Contributor(s): Dr. Breanna F. Powers and Dr. Julie A. Heath

Key Resource(s):

• Global climate change and wildlife in North America. Wildlife Society Technical Review 04-2
• Impacts of climate change on the future of biodiversity

Introduction

Figure 1. The predicted extinction risk (by percentage with 95% CIs) from climate change by different regions, colors represent a gradient from least to most extinction risks (green to red) based upon the number of relevant studies (n). Figure is from Urban (2015). Reprinted with permission from AAAS. Any use of this figure requires the prior written permission of AAAS

Figure 2. Conceptual diagram showing how increased water temperatures and pCO₂ (partial pressure of carbon dioxide) affect the early life stages of fish. Where arrow direction indicated increasing rate ( ↑ ), decreasing rate ( ↓ ), or both directions depending on other environmental variables ( ↕️ ). Figure is from Pankhurst and Munday (2011).

Global climate change will affect ecosystem functions and cycles such as nutrient, hydraulic, and carbon cycles, changing aspects of environmental conditions such as temperature, soil moisture, and precipitation. Wildlife species are adapted to their environments and changes to the environment and habitat conditions will mediate effects, either directly or indirectly, on species survival, fecundity and ultimately population persistence. The ability to adapt to changing habitat conditions as a result of climate change will differ across individual species and between populations. Some wildlife species may be more vulnerable to climate change than other species (Figure 1). Vulnerability is often linked to particular life-history traits (e.g., specialized habitat needs or limited dispersal abilities, see Pacifici et al. 2015P for a review on species vulnerability to climate change) or genetic composition. For example, grassland birds may be more vulnerable to changing climate than forest birds as forests can buffer change more so than grasslands. Projected changes in the climate will generally have adverse effects of wildlife populations, though there are some species coping with climate change or benefitting from environmental change. For example, American kestrels (Falco sparverius) have shifted their breeding phenology to earlier in the year and may now raise two broods of young within a breeding season.

The Influence of Climate Change on Wildlife and Habitats

Climate change effects on wildlife include increases in disease and changes to pathogen distributions, patterns, and outbreaks in wildlife changes in range distributions and shifts in latitudinal and elevational gradients; changes in phenology or the timing of life cycle events that may create phenological mismatches and extinction or population reduction. The effects of climate change across a species’ range will most likely not be homogenous, meaning it can vary substantially, especially if a species’ range spans across different continents as exhibited by many migratory birds. Other changes in habitat include shifting vegetation (i.e., tree-lines are shifting to higher elevations), changes in nutrients in plants, earlier snowmelt and run-off, increase in invasive species, warming of streams and rivers, reduction or degradation of habitat (i.e., glacial melt), and an increase in large wildfires and droughts.

Although climate change effects on wildlife often are linked to species-specific traits, there are general impacts associated with taxonomic groups. For fish it can affect reproduction, growth, and recruitment(Figure 2). Cold-water fish such as inland North American species are highly affected with the warming of streams and rivers. Amphibians are highly sensitive to their environment and changes in temperature and moisture can affect development, range, abundance, and phenology. In reptiles, climate change effects can alter thermoregulation patterns, affect female reproduction and in some species, change sex ratios with increasing temperature. Furthermore, for many bird species the timing of migration and other phenological events are affected by climate change. Range shifts, growth size, and survival are linked to climate change for mammals. Arctic marine mammals are closely linked to sea ice dynamics and a changing climate will affect these dynamics. Therefore, it is increasingly important for conservation and management plans to consider the effects of climate change on wildlife and habitat for the geographic location.