Across the planet, subarctic environments are warming faster than the southern regions, partly due to the loss of the highly-reflective surfaces of snow and ice. This amplified warming is having measurable impacts on marine and land ecozones, and on communities who live and rely on them. At the boundary of the discontinuous and continuous permafrost zones, and at the northern extent of the boreal forest, the coastal subarctic ecoregion known as the Hudson Bay Lowlands represents the largest contiguous wetland complex in Canada, and third largest in the world, spanning an area of 373 700 km2. The Hudson Bay Lowlands is a prime example of a geography poised to experience dramatic rates of climate change in the coming decades. We carried out a survey of existing research to determine (1) what are the impacts of climate change on terrestrial and freshwater ecosystems in the Hudson Bay Lowlands? and (2) how do environmental processes in this region mediate these impacts? To address these research questions, four illustrative case studies have been selected which span a range of interconnected subsystems within the Hudson Bay Lowlands: snow, trees, ponds, and frogs. Using existing thresholds identified in the literature for these key impacts and mediating factors, we investigate how different climate change scenarios may (or may not) lead to the crossing of key ecological tipping points, and also show how this approach can be applied across contexts to examine how wetlands and their thresholds respond to environmental changes.