A Liberate Tate performance showing the rise in 'Parts per Million' of carbon dioxide levels from 1840 to 2013. © Martin LeSanto-Smith

Last year Sunniva Taylor and Jamie Kelsey-Fry attended London’s Tate Modern Art Gallery Members AGM to represent 15 fee-paying Tate Members who had written to the Tate Members Council to raise concerns over BP's sponsorship of Tate. After five months, they received a dismissive response from the Council. This evening, Sunniva and Jamie are returning to resign their membership. This is the statement they’re going to make:

I am Sunniva, and this is Jamie and we are currently Tate members. We have both been so for quite a while. However, we're here today to resign our membership. Why? Because we can no longer justify to ourselves being members of an organization that is in bed with BP – an oil corporation whose very business model is reliant on destroying the climate, and thus life on earth as we know it.

This gallery and others in the Tate portfolio are sponsored by BP: you cannot avoid the BP logo whichever way you turn. After last week’s re-launch of Tate Britain this is particularly striking, as you may well have noticed on your way in this evening. In displaying the BP brand so prominently, Tate is normalizing it in the public consciousness – giving it social credibility, a sparkly sheen – by associating the logo with art, aesthetics and creativity.

But BP stands for destruction, not creation. Its core business model is exploring for and extracting fossil fuels, especially oil. According to peer-reviewed research last month, BP is solely responsible for almost 2.5 per cent of global historic greenhouse gas emissions, making it the third most responsible company for causing climate change in the world.

It is not only a question of historic responsibility. The International Energy Agency (IEA) says we must leave two thirds of known reserves in the ground in order to stay within the limits of climate safety yet BP continues to spend billions of pounds searching for new sources of oil and gas, which we cannot possibly burn. Climate scientists are in broad agreement of the need to stay below the level of 350 parts per million of atmospheric carbon to stabilize the climate. But in the very week that the BP Walk Through British Art display opened in May, we passed 400 parts per million.

Friends, there is nothing controversial or radical about what we are saying. These are the words of scientists and economists. What is controversial is Tate’s refusal to acknowledge the reality of this situation. What is radical is Tate being complicit with companies whose fundamental business model is based on the destruction of a safe and stable climate on this planet.

Quitting Tate membership isn’t a decision that we are making lightly. We both love art, and for both of us coming to the Tate has been an important part of our social and cultural lives in London. I remember lying on my back watching the beauty of the created sun setting in the Turbine Hall – reflecting on the rhythms of the earth and the power of the cycles in which we live. The smallness of myself and the bigness of the world – human ingenuity and creativity – and how in one piece of art I was being connected to all of that. But in taking sponsorship from BP, Tate is pulling a veil across just how catastrophic climate change is, and who is responsible. And we find that as members we have no power to change this practice.

Last year we wrote to the Tate Members Council alongside 15 other members to air our serious concerns about BP sponsorship and we came to the AGM to ask questions. We understand that our questions were also considered by the Tate Members Council at their last meeting. After five months we received a letter in which we were told that the Council itself could not make any representation on our behalf and that therefore we needed to put our objections to the Trustees themselves.

It is a disappointment to us that while we were looking for genuine engagement on a controversial issue that many members have raised, we seem to have received a message of ‘just pay your fees and don’t ask questions’. This position isn’t possible for us, which is another reason why we are resigning. We will continue to loudly object to Tate’s endorsement of the destruction of our climate, but we will do so as visitors, and perhaps by engaging with the many groups creating artistic interventions that are dramatically problematizing this ongoing arrangement with BP.

Please, fellow members, we urge you to consider what you are a part of. We are not alone in holding these concerns. Last year Tate said in a reply to a freedom of information request that it had received more representations raising concerns about BP’s sponsorship than any other issue since the oil company became linked to the gallery in 1990. Meanwhile almost 10,000 members and visitors signed a petition calling for the end of BP sponsorship. We hope that the damage that Tate is doing to its international brand through this long-standing association with one of the world’s most controversial companies isn’t irrevocable. We hope to return one day to being members when the Tate really does live up to its stated vision to ‘demonstrate leadership in response to climate change’.

Perhaps if the Tate makes this forward focused and creative step many others, currently put off by the BP brand will be convinced enough to do the same.