The alarm has sounded. After decades of climate research, the evidence is unequivocal: human activity is changing our climate, leading us towards an unpredictable, volatile future ^[1]. Extreme weather events such as flooding, drought, and wildfires pose unprecedented risks to human prosperity - not in the future, but now and with increasing severity ^[2]. The case for action is clear.

While responses to date have largely focused on future change, reflecting an assumption that increased carbon output produces a linear 'warming', more recent research reveals a more complex, non-linear picture ^[3]. While the nature of our climate system makes exact predictions impossible, the trend (and risk) is undeniable. Put simply, the more we continue to emit now, the more catastrophic our future becomes. While scientists debate the exact level, the non-linear nature of the Earth's climatic system means that there is point at which our warming will trigger 'feedback' loops within the Earth system, locking us into unavoidable, disastrous change ^[4].

As the latest report from the Intergovernmental Panel on Climate Change (IPCC) explains, there is a huge difference between an average increase of 1.5 degrees and 2 degrees - the limit agreed to by governments under the 2015 Paris Agreement - with the latter suggested by some scientists as sufficient to 'tip' the climate into an irreversible cycle of warming. The UN Secretary General describes this as "a direct existential threat", noting that "If we do not change course by 2020, we risk missing the point where we can avoid runaway climate change, with disastrous consequences for people and all the natural systems that sustain us." ^[5]

According to the IPCC, allowing warming to increase to 2°C instead of 1.5 puts hundreds of millions more at risk of death, resulting in close to the entire loss of the world's coral reefs, annual heat waves and wildfires, flooding, drought and all the associated food insecurity (and political instability) that this ties to. In the words of one leading scientist, "There is a growing recognition that 2°C is dangerous." ^[6]

Climate models are constantly being updated, however, this uncertainty is no reason to wait. Historical data reveals that climate change is occurring earlier and more rapidly than expected ^[7], with increasing impact in the human realm. As risk analysts from the New England Complex Systems Institute write, "We have only one planet... Even a risk with a very low probability becomes unacceptable when it affects all of us - there is no reversing mistakes of that magnitude." ^[8]

Despite their call for urgent, transformational response, it's important to note that the IPCC reflect the conservative end of climate science, collating studies from around the world and producing consensus assessments - meaning that there is a whole swathe of research beyond and outside the scope of what the IPCC is reporting on. In short, their dire prognosis reflects a best-case scenario - and yet, governments and business continue to act as if it were a worst-case scenario ^{[9] [10]}. This lack of leadership threatens us all.

As a result of human activity, our climate is warming, producing volatile conditions that threaten the climatic stability on which our collective prosperity has built. Due to the non-linear nature of warming, our ongoing emissions risk taking us to a point where the climate 'tips' - producing ever-increasing volatility irrespective of reduced emissions . This risk is unacceptable. New Zealand needs to join the nations that are leading climate change action. ^[11]