Pacific Island nations have told the United Nations climate change summit in Paris they are already feeling the effects of climate change and urgent action is needed.
They say climate change is not just an environmental issue, but a humanitarian one.
The two-week United Nations Framework Convention on Climate Change Conference is being billed as the last chance to nail down a global deal to tackle climate change.
The president of Kiribati, Anote Tong, says his country may no longer exist in just 60 years because of rising sea levels if something dramatic is not done.
He says if the issue of climate change is not addressed very soon, it could be the final challenge for all of humanity.
"The science is very clear. And we have gone well past debating the technicalities of climate change. I don't believe that this should be the focus of our discussions here today. Rather the question should be: are we truly ready to take the necessary steps and make the necessary sacrifice in order to ensure that those in the front line will be able to stay in their homes."
The Pacific region is responsible for just 0.03 per cent of the world's total greenhouse gas emissions, but it is already feeling the effects of climate change - warming oceans, drought, coral ecosystems destroyed, extreme weather events, ocean acidification and rising sea levels.
Negotiators from 195 countries are seeking a deal aimed at reducing carbon emissions and limiting global warming to two degrees above pre-industrial levels.
But leaders from the Pacific are calling for a target of a 1.5 degree temperature rise by the end of the century, saying anything warmer would be devastating for them.
The Tuvalu prime minister, Enele Sopoaga, says all countries must commit to substantial action on mitigation, and feel obliged to implement nationally determined commitments - not just communicate them.
He says Tuvalu's survival depends on the outcomes of the conference.
"Just imagine you are in my shoes. What would you do? I believe no leader around or in this room carries such a level of worry or responsibility. No leader here in this room can say a total of its territory and all its citizens will disappear if we were to allow temperature increase to anything more than 1.5 degrees."
Mr Sopoaga says there should be a 'loss and damage' chapter in the final COP 21 agreement, which would mean vulnerable countries are compensated for the effects of climate change.
Many wealthier countries oppose such a provision, and the next two weeks of negotiations will be crucial as to whether 'loss and damage' makes it into the final agreement.
Mr Sopoaga says the onus is on industrialised nations to give the Pacific a fighting chance.
"Cyclone Pam earlier this year has already demonstrated devastating effects on our economy. We applaud and thank those who responded with sympathy to our call. But we want to say ad hoc assistance such as this is not enough.
"We need a permanent mechanism for loss and damage anchored in the Paris treaty that gives us assurances that necessary response to climate change is there and will be forthcoming."
The president of Nauru, Baron Waqa, told leaders that after years of excess and wilful ignorance, the climate bill has finally come due.
He says right now it is the smallest and most vulnerable who are paying the price, but no country will escape forever.
"Small island communities pay in the droughts that destroy livelihoods, and the record cyclones that steal lives. We see a small toll exacted every day as our shorelines are slowly eroded."
The prime minister of Fiji, Frank Bainimarama, says Fiji is already looking at relocation options for its communities already being affected by climate change.
He says he is also in discussions with leaders from Kiribati and the Marshall Islands about their people taking permanent refuge in Fiji.
"We in the Pacific face the prospect of losing three nations all together. The low-lying atolls of Kiribati, Tuvalu and the Marshall Islands. And even in a country like Fiji, with our mountainous volcanic islands, we too are in the process of relocating 45 communities and have so far identified 830 that are at risk.
"In a worst case scenario Fiji has offered to explore the issue of permanent refuge to the people of our closest neighbours - Kiribati and Tuvalu. A sensitive discussion we hope to continue in earnest in our moral responsibility."
The prime minister of Papua New Guinea, Peter O'Neill, says his country is the home of the first climate change refugees, as people from Bougainville's Carteret Islands are being relocated due to rising seas.
He says there are entire Pacific Island nations facing extinction, which could mean tens of thousands of years of culture are lost.
"These countries, like many, have the right to exist in this world. In the Pacific lives are being lost to extreme drought and frost and also the most devastating tropical storms recorded in recent history strike each year. This ongoing disaster must be stopped. And support must be given to the victims of climate change so they can rebuild their lives. We in this room today have the power to do so."
The United Nations also heard from the leaders of Vanuatu, Federated States of Micronesia, Palau, Samoa and the Cook Islands.