"The science is irrefutable – climate change is already impacting ecosystems and communities around the world, with increasingly frequent and severe storms, floods and droughts; melting polar ice sheets; sea level rise and coastal inundation and erosion; and impacts on biodiversity including species loss and extinction.
"The Council's role is to support the region and its communities to better understand and proactively respond," he said.
"The IPCC's Special Report in October 2018 stated that we have twelve years to turn greenhouse gas emissions around to limit global warming to the Paris Agreement target of 1.5-degrees, or face an uncertain future.
"This requires 'rapid and far-reaching transitions in energy, land, urban and infrastructure (including transport and buildings), and industrial systems.
"Everyone has a role to play in delivering the change required."
The decisions came after environmental lobby group Extinction Rebellion NZ protested at several venues across New Zealand last month.
"Extinction Rebellion asked us to declare a 'climate emergency' and, after debate and careful consideration, that is what we have done. We are not at odds with Extinction Rebellion's desire to see people sit up and take urgent notice and urgent action. Our declaration today confirms that," Scott said.
Nelson Mayor Rachel Reese said climate change leadership requires smart thinking and proactive decision making.
"We're going to need a new way of thinking and working to meet the expectations of our youth and of the next generation.
"Our region already has a reputation as a leader in scientific, environmental and business innovation. Council wants to work alongside our business and community leaders to take an innovative approach to meet this challenge," she said.
"Local Government plays a critical role in leadership on issues that affect us all, and today this Council has proven the value of local democracy.
"By making the declaration, Council is committed to looking at how its plans, policies, and work programmes can support action to address the climate emergency, and ensuring that a climate emergency strategy is embedded in all future Council strategic plans."