More frequent extreme rainfall events would only be compounded by a sea level expected to be 15cm to 30cm higher by 2050.
Low-lying parts of the city – including the CBD, eastern bays, Onehunga, Māngere Bridge, Devonport and Helensville – would be the most vulnerable to inundation.
Auckland Council has responded through various measures, namely its Low Carbon Auckland effort and the in-development Climate Action Plan.
These aimed to ramp down the city's greenhouse gas emissions while preparing for the wide-ranging impacts of a warming world.
A declaration of an emergency was meant to spell out just what a crisis climate change would be – and was proving already.
Yet it didn't commit the council to any new specific plan or code.
As it stood, climate change wasn't included in the formal definition of an "emergency" under the Civil Defence and Emergency Management Act 2002.
A declaration of a "climate emergency" also had no other inherent statutory or legal implications.
As such, the declaration was merely a signal of the council's intention to put climate change at the centre of work programmes and decision making.
The council's Environment and Community Committee chair Penny Hulse asked council staff to look at how other cities and bodies had officially declared climate change an emergency.
This call came at the request of activist group Extinction Rebellion, which compared the scale and speed of mobilisation needed to that of countries at the outbreak of World War 2.
Nearly 600 councils and governments have declared a climate emergency worldwide – the UK, Irish and Welsh parliaments among them.
Here, Environment Canterbury last month became the first council in New Zealand to do the same; the Kāpiti Coast, and the Waitakere and Waitemata Auckland local boards followed suit soon after.
While there is no standardised or official common meaning to the declarations, jurisdictions have been using the declarations to underscore the urgency and importance of taking action on climate change.
So what is Auckland Council actually doing?
Auckland's current targets were to knock back greenhouse gas emissions by 10 to 20 per cent by 2020, 40 per cent by 2040 and 50 per cent by 2050, based on 1990 levels.
The council was in the process of reviewing the Low Carbon Auckland plan and developing its catch-all action plan that covered combating climate change, as well as adapting to it.
Te Tāruke-ā-Tāwhiri: Auckland's Climate Action Framework was meant as the main framework for delivering on this emissions reduction target, as well as increasing Auckland's resilience to climate change impacts, through local action plans.
Elsewhere, the council was working alongside national groups like the New Zealand Climate Leaders Coalition, and global ones like C40, while driving initiatives like home retrofits, electrifying the bus fleet and making its own buildings greener
And while there were no rules to give teeth to an official "climate emergency", the council did happen to be obligated under several laws.
Both the Local Government Act and the Resource Management Act, for example, required the council to plan for, and adapt to, the effects of climate change, to "manage and minimise" impacts.
Under legislation like the Land Transport Management Act, there's a further mandate to slash emissions from transport and drive a shift to greener alternatives like walking, cycling, public transport and electric vehicles.
So are emissions coming down?
Well, yes – but there's still a long way to go.
In 2016, the most recent year recorded, Auckland's gross emissions were 11,326 kilo-tonnes of carbon dioxide equivalent (kt CO2e) and when carbon sequestration from forestry was included, net emissions were 10,128 kt CO2e.
Transport and stationary energy were naturally dominant sectors, accounting for 43.6 per cent and 26.6 per cent of gross emissions, respectively.
Carbon dioxide (CO2) contributed 83.1 per cent, methane (CH4) 10.5 per cent, nitrous oxide (N2O) 1.7 per cent and other greenhouse gases 4.7 per cent.
That marked a drop from 2015 levels and was driven by decreased emissions from energy, and improvements in industrial processes, along with forestry sequestering more carbon.
However, it wasn't clear that this decrease – which came after years of rising emissions – marked the start of a new trend.
And in any case, Auckland still had to slash its emissions by 24.7 per cent to 33.0 per cent by 2020, 49.8 per cent by 2040 and 58.1 per cent by 2050, to meet its reduction targets.
Auckland's Climate Action Plan, currently under development, would set an emission target consistent with the Paris Agreement aspiration of 1.5C maximum temperature rise and a path to rapidly ramp down emissions.
Will a climate declaration actually make a difference?
Ahead of today's meeting, councillors were told that a declaration "would likely increase the visibility of Auckland's political commitment to leadership on climate action".
Not doing so, on the other hand, might "result in a perception of or reputational risk in not acknowledging the urgency of acting on climate change".
Extinction Rebellion spokesperson Cordelia Lockert said a yes voted demonstrated the council's commitment to resolving the climate crisis.
"Last year the UN warned we only had 12 years to save the planet we know and love from climate breakdown," Lockert said.
"Their latest report says if we don't act soon, one million species face extinction, undermining the life support systems we all rely upon."
"The council needs to tell the truth and create a citizen's panel to ensure the climate crisis is at the heart of everything we do in Auckland."
But University of Canterbury Associate Professor Dr Bronwyn Hayward – who was the only New Zealand author on the landmark IPCC report that Lockert cited - wasn't sure the declaration was an entirely positive thing.
While it was good that there was public recognition of the issue, it wouldn't be helpful if the call was based around panic than practical solutions, Hawyard said.
"I'm increasingly anxious about these calls for climate emergencies, because in many ways local councils are damned if they do and damned if they don't at the moment," Hayward said.
"It's fair enough to say that they are under pressure to accept that they realise that there is a very serious crisis, but I'm much more concerned about the actual action that flows from that."
Hayward, an expert in political science and international relations, and the director of the university's Sustainable Citizenship and Civic Imagination research group Hei Puāwaitanga, was also concerned about the potential anxiety that such gestures could be causing to young people.
"We can't maintain this level of intensity - we have to get quite practical and a lot of that is very boring," she said.
"It's attending to those first principles of lowering carbon emissions in the cities, like changing the way we build our buildings, tackling freshwater supplies and making sure our housing is as dense as we can make it, live-ably."