But most charities will probably think climate change is best left to environmental campaign groups such as Greenpeace and WWF.
For everyone else in the sector, climate change might seem irrelevant. Why bother to sign up to something that does not pertain to your core business?
The sector's ambivalence about taking action on climate change reflects a reluctance that is widespread within society generally. For example, it is typical of representatives of higher education institutions to say: "What can one small university do about climate change?" This sort of attitude leads to universities running symbolic projects, such as glass or paper recycling schemes, that are showcased as examples of wider environmental responsibility. At the same time, the universities in question probably have little idea what their carbon footprints are or how they can reduce them.
The parallels between the higher education and voluntary sectors are glaringly obvious. University managers are primarily concerned with hitting performance targets based on criteria ranging from numbers of students to their output of academic publications.
Similarly, third sector managers will be focused on key performance indicators that leave no room for thinking about reviewing working practices and investment priorities so as to respond to climate change.
But the higher education sector's ambivalence about climate change was effectively challenged by the use of a tool that is loved and loathed in equal measure - the league table.
People & Planet's Green League ranks universities according to their environmental performance. Published in June, it has prompted more and more vice-chancellors to send out a clear message: it's not only the teaching that counts - reducing our carbon footprint is important too.
What would it take to inspire a sector-wide initiative to transform charities' commitment to tackling climate change? Is it possible that environmental audits will ever be as important to chief executives as financial audits? Could children's homes or hospices become models of low-carbon, energy-efficient good practice? What about a dedicated 'transition fund' to enable the voluntary sector to transform the quality of its physical estate?
Unless we start to get our act together, The Third Sector Declaration on Climate Change will simply be yet another example of empty promises.
- Ian Leggett is director of the poverty and environmental charity People & Planet.