Bike Auckland chairwoman Barb Cuthbert said she welcomed the research results "as more compelling evidence why building safe and attractive walking and cycling routes is productive and valuable in major centres across NZ".
Cycling Action Network spokesman Patrick Morgan said the research came as no surprise.
"Cycling is the best bang for the buck in transport investment," he said.
"When you are facing a climate crisis, a road safety crisis, and a health crisis, building safe and attractive cycleways is a no-brainer."
Co-author Dr Caroline Shaw said the 1 per cent reduction in carbon emissions was likely to be a conservative estimate, as shorter car trips - those most likely to be replaced by walking or cycling - typically had higher per kilometre emissions.
"It is also important to note that we would expect the more extensive networks of cycle lanes which some councils are now putting in, to have an even bigger response," she said.
If the same level of investment was made nationwide, it could reduce the country's carbon dioxide emissions by at least 0.23 million tonnes over three years, the researchers said.
Building new cycle paths and walkways also appeared to reduce car ownership in the two cities.
The researchers used a variety of methods to collect information on car usage, conducting face-to-face interviews with householders, analysing odometer readings from licensing data and reviewing details on car ownership from the New Zealand Household Travel Survey.
The data from New Plymouth and Hastings was compared with information from Whanganui and Masterton - two cities which received no additional government funding for cycle ways or walking paths.
Hastings Mayor Sandra Hazlehurst said Hastings was one of the first cities in New Zealand to receive government funding for cycle ways, and since 2010 the council has been committed to provide walking and cycling access for the community.
"It contributes enormously to the health and wellbeing of our communities as well as improving the environment.
"We have a 15 year programme for the i-Way network, with our investment reaching approximately $15 million for new cycle ways. As this extensive programme continues in the future, it will extend the cycle trails and fill in gaps in the existing network.
"I am proud that Hastings is regarded as one of the best places in the country to cycle with our hugely successful i-Way programme making up some of Hawke's Bay's almost 200 kilometres of cycling trails."
Shaw said the research clearly demonstrates that people are prepared to substitute cycling and walking for car journeys.
"We already know that putting in cycling and walking infrastructure reduces congestion and makes cities nicer places to live, as well as being highly cost effective. We now also know that it reduces carbon emissions."
