Climate change: Northland's marine species to feel the heat from the 2030s
If our greenhouse emissions continue to soar, Northland's marine life will face extreme temperatures on an average day in the 2030s which could lead entire ecosystems to collapse, new research warns. In a paper published in the journal Nature , researchers used modelling to work out when 30,652 species around the world would suffer extreme heat stress. The study defined this point as the time when an environment's average temperature for at least five years in a row would exceed the warmest conditions the species had experienced between 1850 and 2005. For the oceans around Northland, this milestone would be reached in the 2030s if the world continued to emit high levels of greenhouse gases, the models projected. Study co-author and University College London researcher Dr Alex Pigot said marine life in the oceans north of New Zealand would be exposed to dangerous heat "as early as 2030 to 2040, [this] will then spread to more southern regions over the ensuing decades". READ MORE: * Climate change, pollution threaten NZ's marine environment * New Zealand native species under threat due to marine heatwaves * New Zealand waters seeing fastest rate of acidic change in 25 million years Some plants and animals in the oceans and then on land will increasingly feel the heat which could tip them into extinction as the century progressed, the study found. Pigot said a rapid temperature rise made the collapse of an ecosystem much more likely. "When species losses occur gradually then, to some degree these may be partially offset by the arrival of new warmer-adapted species from elsewhere. However, if losses of biodiversity occur abruptly then we would expect the disruption to the functioning of ecosystems to be much more severe." Human civilisation made it much harder for species to adapt to climate change, Pigot said. "In addition to climate change, we are impacting the environment in many ways [for example the] roads and conversion of habitat for farmland or cities that fragments the environment reducing the ability of species to move through landscapes and track their preferred climates." But there was still time to make a difference, Pigot said. The findings also demonstrated climate change mitigation could save thousands of species. "By holding warming below 2C, we can effectively 'flatten the curve' of how climate risks to biodiversity accumulate over time, delaying the exposure of the most at-risk species by many decades and averting exposure entirely for many thousands of species. This will buy valuable time for species, ecosystems and the human societies that depend on these systems, to adapt," Pigot said. "The second thing that we can do is to expand and improve governance of protected areas so that species can maintain healthy populations and are free to disperse through the land or seascape as conditions change. This way we will give biodiversity the best chance of riding out the climate crisis." Study co-author and University of Cape Town researcher Dr Christopher Trisos said the study did not predict how each species would react to extreme heat. "We would expect there to be extinctions, but not necessarily we simply have no evidence of the ability of these species to persist after this point," he said. University of Auckland marine scientist Dr Simon Thrush said climate change would stress marine species in other ways, beyond heating their environment. Waters would become less oxygenated and more acidic, ocean currents would shift and increasingly extreme storms could rough up sea floors and boost sediment run-off from land. Thrush said expected changes in the way the upper layers of the oceans mixed could curb the growth of microscopic algae, "the base of the oceanic food chain [that] influence[s] the food resources that are there for fish, birds, whales and everything else". Species that live or breed on the coast or in estuaries could be squeezed out and isolated as the sea level rises and communities build sea walls, he said. "All of these things go on at once, though not all the impacts occur simultaneously," he said. "In all of the situations, there will be winners and losers. It's not just all bad." Resilient ecosystems would be best placed to adapt to the new conditions, with marine species once living off Northland perhaps settling around areas such as Wellington, Thrush said. "We might expect to see some potentially rapid changes." Nearly 90 per cent of all native seabirds, 80 per cent of all shorebirds and 22 per cent of marine mammals are already threatened or at risk of extinction, according to the Department of Conservation.