Key indicators of Arctic climate change: 1971–2017

Abstract

Key observational indicators of climate change in the Arctic, most spanning a 47 year period demonstrate fundamental changes among nine key elements of the Arctic system. We find that, coherent with increasing air temperature, there is an intensification of the hydrological cycle, evident from increases in humidity, precipitation, river discharge, glacier equilibrium line altitude and land ice wastage. Downward trends continue in sea ice thickness (and extent) and spring snow cover extent and duration, while near-surface permafrost continues to warm. Several of the climate indicators exhibit a significant statistical correlation with air temperature or precipitation, reinforcing the notion thatincreasing air temperatures and precipitation are drivers of major changes in various components of the Arctic system. To progress beyond a presentation of the Arctic physical climate changes, we find a correspondence between air temperature and biophysical indicators such as tundra biomass and identify numerous biophysical disruptions with cascading effects throughout the trophic levels. These include: increased delivery of organic matter and nutrients to Arctic near-coastal zones; condensed flowering and pollination plant species periods; timing mismatch between plant flowering and pollinators; increased plant vulnerability to insect disturbance; increased shrub biomass; increased ignition of wildfires; increased growing season CO 2 uptake, with counterbalancing increases in shoulder season and winter CO 2 emissions; increased carbon cycling, regulated by local hydrology and permafrost thaw; conversion between terrestrial and aquatic ecosystems; and shifting animal distribution and demographics. The Arctic biophysical system is now clearly trending away from its 20th Century state and into an unprecedented state, with implications not only within but beyond the Arctic. The indicator time series of this study are freely downloadable at AMAP.no.

Increased high‐latitude photosynthetic carbon gain offset by respiration carbon loss during an anomalous warm winter to spring transition

“…The northern high latitudes are warming faster than the global average, with the highest rate of warming observed during the cold season (Box et al, ; Graham et al, ; Walsh et al, ). Such changes in temperature seasonality will have a stronger influence on shoulder season carbon exchange and thus play a major role in determining the future trajectory of northern high‐latitude ecosystems as carbon sinks or sources to the atmosphere (Commane et al, ; Ueyama, Iwata, & Harazono, ).…”

“…High‐latitude ecosystems are generally temperature or radiation limited, and therefore, warming has a primary control on the seasonal change in photosynthesis or respiration (Parazoo et al, ; Figure ). Climate warming promotes earlier landscape thawing, a reduction in spring snow cover, earlier onset of vegetation productivity, and longer growing seasons (Box et al, ). These changes tend to benefit photosynthesis more than respiration (autotrophic and heterotrophic) and therefore contribute to stronger net CO 2 uptake in the early growing season (Assmann et al, ; Myers‐Smith et al, ).…”

An integrated index of recent pan-Arctic climate change

“…SWIPA 2017 took the view of providing information on multiple Arctic climate elements culminating in a time series comparison of six indicators beginning in 1970-1982 with yearly resolution (AMAP 2017, figure 11.2). This set of initiators has been updated and expanded as in the companion paper by Box et al (2019). The set of time series we use are listed in table 1 and graphed in figure 1.…”

“…Arctic cryospheric climate indicators are: Arctic Oscillation for Winter, Winter surface air temperature north of 60°N, Permafrost temperatures for northern Alaska, Tundra greenness index, sea ice extent March, sea ice extent September, number of snow days in spring (May-June), Greenland ice mass balance, Alaskan glacier index, Spitsbergen glacier index. For more details seeBox et al (2019).…”

A Framework for the Development, Design and Implementation of a Sustained Arctic Ocean Observing System

“…Nowhere on Earth are the effects of climate change more apparent than in the Arctic. Long-term temperature records clearly show that the region is warming at more than double the global average (Richter-Menge et al, 2018;Box et al, 2019), an effect known as Arctic amplification. The rapid warming, identified in early climate models (e.g., Manabe and Stouffer, 1980), impacts all areas of the Arctic, from the tundra to the highest mountains, from to the deepest part of the Arctic Ocean through to the upper levels of the atmosphere (AMAP, 2017).…”